No abstract available

[en] It is argued that the dielectric-breakdown model has an upper critical η_c equal to 4, for which the clusters become one dimensional. A renormalization group treatment of the model is presented near the critical η

[en] Highlights: • AIEE and CIEE active fluorophores (MOTPAs) containing triphenylamine were synthesized. • The single branch fluorophores (SMOTPA) presented a tunable emission. • Fluorescence imaging experiments of TMOTPA in living A549 cells proved its potential for practical applications.

[en] A study on the Interaction of Water, Methanol and Ethanol with Zirconia powder investigated the Hard and Soft Agglomeration of Hydrous Zirconia powder [ [Zr₄(μ-OH)₈(OH)₈(H₂O)₈]. xH₂O] by using Fourier Transform Infrared (FTIR) Spectroscopy found that alcohol washing on the precipitation of Zirconia pervented the bridging of hydroxo group which caused the hard agglomerate formation. The Neutron Activation Analysis Technique (NAA) was applied for quantitative determination of Zirconia and the structure of zirconium compounds were done by X-Ray Diffraction spectroscopy (XRD) Technique

[en] Aggregation of protein is widely observed in our daily life. For example, cooking is manipulation of protein state. Main cause of various human diseases such as Alzheimer’s and Parkinson’s diseases is also considered to be aggregation of protein. One of model proteins is ovalbumin (OVA), which is a major protein in egg white. An OVA aqueous solution aggregates at high temperature and forms gel like sunny-side up above the threshold concentration. This phenomenon has been researched thoroughly from the viewpoint of turbidity, rheology, spectroscopy, scattering and so on. Then we, as chemists, think the next step for this research is manipulation of the aggregation state by modifying the chemical structure. Kawachi et al. concentrated on the N-terminal amphiphilic peptide region (pN_1_-_2_2) and proved that this peptide region enhances the strength of OVA gel from the viewpoint of rheology. In contrast, aggregation ability of OVA without this peptide region (pOVA) is dramatically reduced. We assume that the reason for this phenomenon originates from the amphiphilic nature of the peptide. The aim of this research is to clarify the role of pN_1_-_2_2 and the relationship between the microscopic chemical structure and the macroscopic physical properties. To clarify the mesoscopic structure, we conducted a SANS measurement at GP-SANS, High Flux Isotope Reactor at ORNL. Samples are solutions or gels of OVA, pOVA, peptide and their mixture with various concentrations before and after heating. pH of samples was set to 7, which is common condition for the application of OVA and their derivatives. We observed a strong upturn at low-q region in SANS curves for pOVA solutions/gels after heating. This behavior is similar to a phase separation of well-known poly(N-isopropylacrylamide) (PNIPA) solutions. From this result, we can see that the lack of amphiphilic peptide region makes the OVA solute unstable and promotes aggregation. In contrast to this, addition of amphiphilic peptide region does not change SANS profiles noticeably even after heating. This means that the peptide enhances the strength of gels without changing the original structure and is desirable for application.

[en] In this paper experimentally observed trajectories of particles undergoing acoustically induced interaction and agglomeration processes are compared to and validated with numerically generated trajectories based on existing agglomeration theories. Models for orthokinetic, scattering, mutual radiation pressure, and hydrodynamic particle interaction are considered in the analysis. The characteristic features of the classical orthokinetic agglomeration hypothesis, such as collision processes and agglomerations due to the relative entrainment motion, are not observed in the digital images. The measured entrainment rates of the particles are found to be consistently lower than the theoretically predicted values. Some of the experiments reveal certain characteristics which may possibly be related to mutual scattering interaction. The study's most significant discovery is the so-called tuning fork agglomeration [T. L. Hoffmann and G. H. Koopmann, J. Acoust. Soc. Am. 99, 2130 endash 2141 (1996)]. It is shown that this phenomenon contradicts the theories for mutual scattering interaction and mutual radiation pressure interaction, but agrees with the acoustic wake effect model in its intrinsic feature of attraction between particles aligned along the acoustic axis. A model by Dianov et al. [Sov. Phys. Acoust. 13 (3), 314 endash 319 (1968)] is used to describe this effect based on asymmetric flow fields around particles under Oseen flow conditions. It is concluded that this model is consistent with the general characteristics of the tuning fork agglomerations, but lacks certain refinements with respect to accurate quantification of the effect. copyright 1997 Acoustical Society of America

[en] Full text of publication follows: The explanation of formation of macroscopic particles agglomerates in rarefied media is an intriguing problem that appears in the context of laboratory and space physics observations. The fast formation of agglomerates in low pressure conditions should be unlikely because of the low density of precursor species, and it is even more puzzling to understand the production of solid-state dust particles in a chemically active plasma. In this work we present evidence of formation of C dust grains in an unusual low pressure plasma confined in a magnetic cusp trap and interpret the major pathways of nucleation of C particles aggregates in a plasma environment of interest both for technological applications and for nuclear fusion research. Optical emission spectroscopy has been used to monitor the methane fragmentation in plasma phase and mass spectrometry has been used to monitor the residual gas during the particles formation in plasma discharge for various Ar/CH₄ gas mixture. The formation of spherical nano-size particles was detected ex-situ by means of AFM (Atomic Force Microscopy) and SEM (Scanning Electron Microscopy) analysis of a collecting Si substrate and in-situ by means of a novel technique based on the induced electrostatic fluctuation spectrum. The chemical nature of the particles was studied ex-situ by means of FT-IR spectroscopy. The production of acetylene compounds (C₂H_x) seems to be a key mechanism for the dust formation in methane plasma. (authors)

[en] We give a theoretical approach to the valence change in small Pr_n aggregates [transition: 4f³(5d6s)²→4f²(5d6s)³], our study limited to n≤4. The quantum-mechanics problem (Anderson Hamiltonian) exhibits various difficulties: f-valence mixing and strong intra-atomic f correlations. For dealing with this problem we use an extension to the mixed-band systems of the Gutzwiller method. The extension is detailed and controlled by an application to the Hubbard s chain, for which the exact solution is known. As the number of f electrons and sites of our Pr_n system is relatively small, we take into account the full f degeneracy. We find the transition for n=3, which is close to the experimental result, n=5. A physical explanation of the phenomenon is proposed

[en] We propose a modeling of the aggregation processes of optical properties and temperature over the heterogeneous landscape in the infrared domain (3-14μm). The main objectives of the modeling are to understand how these parameters aggregate and to study their links at different spatial scales. As the landscape is described at each scale by its radiative parameters, general equations linking the radiative parameters at a given high spatial scale to those at a rough scale are proposed. Then these equations are applied to several synthetic landscapes. An analysis based on a design of experiments is conducted to point out the influence of each of the input factors. The results show the importance of the intrinsic parameters (reflectance, emissivity, and surface temperature) of each surface element and also the directional and spectral behaviors of the aggregated parameters.

[en] Data on the structure of oil asphaltene molecules and their aggregation routes is systematized. The possible phase transitions in asphaltene nano-aggregates and their influence on the properties of oil disperse systems are analyzed. The bibliography includes 204 references.