Experimental evidence on the development of scale invariance in the internal structure of self-affine aggregates

It is shown that an alternative approach for the characterization of growing branched patterns consists of the statistical analysis of frozen structures, which cannot be modified by further growth, that arise due to competitive processes among neighbor growing structures. Scaling relationships applied to these structures provide a method to evaluate relevant exponents and to characterize growing systems into universality classes. The analysis is applied to quasi-two-dimensional electrochemically formed silver branched patterns showing that the size distribution of frozen structures exhibits scale invariance. The measured exponents, within the error bars, remind us those predicted by the Kardar-Parisi-Zhang equation.Comment: 11 pages, 4 figure

Roughening kinetics of chemical vapor deposited copper films on Si(100)

3 pages, 3 figures.The roughening kinetics of copper films synthesized by low pressure chemical vapor deposition (LPCVD) on Si(100) substrates was investigated by scanning tunneling microscopy (STM). By applying the dynamic scaling theory to the STM images, a steady growth roughness exponent (alfa)=0.81 ± 0.05 and a dynamic growth roughness exponent (beta)=0.62 ± 0.09 were determined. The value of (alfa) is consistent with growth model predictions incorporating surface diffusion. The value of (beta), while higher than expected from these models, can be related to LPCVD processing conditions favoring growth instabilities.This work was partially supported by the CSICCONICET cooperation program and by a grant from the NASA New Jersey Space Grant Consortium.Peer reviewe

Kinetics and mechanism of the electrochemical oxidation of nitrite ion dissolved as sodium nitrite in dimethylsulphoxide solutions on platinum electrodes

The kinetics of the electrochemical oxidation of NO2− ion dissolved in DMSO has been studied on Pt electrodes at temperature ranging from 25 to 44°C, by means of potentiostatic E/I curves and by relaxation techniques. The oxidation reaction is explained in terms of a consecutive reaction scheme which involves, as rate-determining step, nitrite-ion discharge on an adsorbed intermediate at the reaction interface, the latter apparently obeying a Langmuir isotherm.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Electrical conductance of hydrogen chloride in dimethylsulphoxide at 25°C

The electrical conductance of hydrogen chloride solutions in DMSO at 25°C has been studied. The limiting molar conductance is 38·7 int mho cm2 int mho cm2/mol. Conductivity data were interpreted with the Fuoss' theory for associated 1-1 type electrolytes. The association constant related to pair formation is 115·7 l/mol. The mechanism of electricl conduction of HCl in DMSO at infinite dilution resembles that of other 1-1 type electrolytes in the same solvent, in which charges are transported by simple entities in a viscous continuum.On a étudié la conductivité électrique des solutions de chlorure d'hydrogéne dans le DMSO à 25°C. La conductivité limite molare est de 38,7 mho int cm2/mol. Les données expŕimentalles de la conductivité furent interprétées d'aprés la théorie de Fuoss pour des électrolytes associé du type 1-1. La constante d'association liée à la formation de paires ioniques simple est 115,7 l/mol. Le mechanisme de la conduction électrique du HCl dans le DMSO à dilution infinie ressemble celui des autres électrolytes du type 1-1 dans le même dissulvant, puisque les charges sont transportées par des entités simples dans un milieu visqueux continu.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Potentials of metals in molten potassium bisulphate

The galvanic behaviour of various metals in molten potassium bisulphate has been investigated, using a hydrogen reference electrode at 260–280°C. A galvanic series is presented to indicate the probable direction of galvanic effects in corrosion cells.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Effect of temperature on the electrical conductance of hydrogen chloride in dimethylsulphoxide

The electrical conductance of solutions of hydrogen chloride in dimethylsulphoxide at temperature from 25 to 45°C has been studied. Results have been interpreted with the Fouss theory for associated 1-1 type electrolytes. Values of the association constant KA and the J parameter have been computed at each temperature. The temperature dependence of the molar conductance is inferred from the theoretical equation and related to the temperature dependence of viscosity.La conductance électrique des solutions de chlorure d'hydrogène dans le diméthylsulfoxyde à des températures de 25 a 45°C a été étudiée. Les résultats ont et́é inteprétés par la théorie de Fuoss pour de electrolytes associées du type 1-1. Les valeurs de la constante d'association KA et du paramètre J ont été calculées à chaque température. La dépendance de la conductivité molare avec la température est déduite de l'équation théorique et référée a la dépendance de la viscosité avec la température.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Gambaran Stigma Masyarakat pada Orang dengan Gangguan Jiwa (ODGJ) di Puskesmas Waibhu

Untuk mengetahui gambaran stigma masyarakat pada penderita gangguan jiwa. Artikel ini menggunakan penelitian kuantitatif. Populasi adalah pasien dan keluarga yang berkunjung ke Puskesmas dengan jumlah sampel 99 orang. Data diperoleh dengan menggunakan kuesioner dan dianalisis secara univariat. Gambaran stigma pada masyarakat di Puskesmas menunjukkan bahwa masyarakat memiliki stigma kategori tinggi sebanyak 34 orang atau 34,3%, dan stigma kategori rendah sebesar 65,7% pada gangguan jiwa. Selain itu, komunitas bertanggung jawab sebesar 74,7% untuk mengalami keterlibatan dengan orang-orang dengan masalah mental dan tahu bagaimana bersimpati dengan situasi psikologis. Kesimpulan: Peneliti berpendapat bahwa masyarakat yang berkontribusi dengan stigma rendah terhadap gangguan jiwa akan menerapkan perilaku yang positif. Sebaliknya, stigma yang tinggi akan menunjukkan sebaliknya. Stigma yang dibuat oleh masyarakat terhadap penderita gangguan jiwa secara tidak langsung menyebabkan keluarga atau orang sekitar penderita gangguan jiwa enggan untuk memberikan penanganan yang tepat

Kinetics and mechanism of the anodic dissolution of nickel in HCl-dimethylsulphoxide solutions

The anodic dissolution of nickel in HCl-DMSO solutions containing different supporting electrolytes has been studied between 20–40°C. The electrodissolution and electrodeposition are predominantly activated electrode processes. At high anodic potentials and in the presence of perchlorate ions at high concentration passivation sets in. A probable reaction pathway is postulated which explains most of the experimental findings. Passivation corresponds to a salt precipitation-dissolution process at the electrode vicinity.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Spatial distribution of pits on stainless steel

The spatial distribution of pits formed on a stainless steel electrode is analysed by means of two stochastic criteria based on the Poisson distribution law. Information is obtained about the character of the location of pits on the electrode surface.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada