Formation of Monodispersed Cadmium Sulfide Particles by Aggregation of Nanosize Precursors

Monodispersed spherical cadmium sulfide particles were used as a model system in order to explain the size selection in the formation of colloids by aggregation of nanosize subunits. Several procedures of mixing the reactants were employed to precipitate these solids and follow the kinetics of particle growth. Efficient numerical simulation techniques for the model rate equations were developed to fit the experimental results. Our results have confirmed the recently proposed mechanism of two-stage growth by nucleation of nanosize crystalline primary particles and their subsequent aggregation into polycrystalline secondary colloids.Comment: 18 pages (with 6 figures) in PD

Raised electrical uterine activity and shortened cervical length could predict preterm delivery in a low-risk population

PURPOSE: To compare diagnostic accuracy of sonographic cervical length (CL) measurement and uterine electric activity assessed by electromyography (EMG) in second trimester regarding prediction of preterm delivery (PTD). ----- METHODS: Prospective study of 308 low-risk women. Shortened CL was defined as ≤25 mm (≤5th centile), while raised EMG activity was defined as the presence of ≥20 action potentials in 20 min of assessment (≥95th centile). Outcome measures were diagnostic accuracy of both tests alone or in combination for prediction of PTD and early PTD (≤34 weeks). ----- RESULTS: The incidence of PTD was 23/308 (7.4%) while the incidence of early PTD was 9/308 (2.9%). Shortened CL and raised EMG activity were significantly related to PTD [prevalence-weighted likelihood ratio (pw-LR) 1.9, 95% CI 1.0-3.5 vs. 9.5, 95% CI 2.5-35.7], but not to early PTD (pw-LR 0.4, 95% CI 0.2-0.8 vs. 0.6, 95% CI 0.3-1.7). Significant predictive value for early PTD was found only if both tests were combined (pw-LR 4, 95% CI 1.3-14.3). ----- CONCLUSION: Shortened CL and raised EMG activity in second trimester have significant diagnostic accuracy regarding prediction of PTD in a low-risk population. However, in order to be useful as a predictor for early PTD both tests must be positive

Mechanisms of Diffusional Nucleation of Nanocrystals and Their Self-Assembly into Uniform Colloids

We survey our research on modeling the mechanisms of control of uniformity in growth of nanosize and colloid particles. The former are produced as nanocrystals, by burst-nucleation from solution. The latter, colloid-size particles, are formed by self-assembly (aggregation) of the nanocrystals. In the colloid particle synthesis, the two dynamical processes are coupled, and both are governed by diffusional transport of the respective building blocks (monomers). The interrelation of the two processes allows for synthesis of narrow size distribution colloid dispersions which are of importance in many applications. We first review a mathematical model of diffusive cluster growth by capture of monomer "singlets." Burst nucleation of nanoparticles in solution is then analyzed. Finally, we couple it to the secondary process of aggregation of nanoparticles to form colloids, and we discuss various aspects of the modeling of particle size distribution, as well as other features of the processes considered.Comment: 26 pages in PDF, including 5 figure

The National Council of Slovenes, Croats and Serbs in Zagreb (1918 / 1919)

The author has reconstructed the emergence, activity and disappearance of the National Council of Slovenes, Croats and Serbs (NV SHS) in Zagreb during the last months of the existence of the Austro-Hungarian monarchy, the short-lived State of Slovenes, Croats and Serbs and the first weeks of the Kingdom of the Serbs, Croats and Slovenes (from March 1918 to January 1919). The basic characteristic of the National Council of SHS and its selfproclaimed state was its intentional temporariness. The aim of the National Council was not the destruction of the Austro-Hungarian monarchy and the creation of an independent state outside of its borders, but the hasty unification of the State of SHS with the Kingdoms of Serbia and Montenegro and the creation of a wider South Slavic state community in the southeast of Europe

Monte Carlo Codes for Neutron Buildup Factors

The point-kernel method is a widely used practical tool for gamma-ray shielding calculations. However, application of that method for neutron transport simulations is very limited. The accuracy of the method strongly depends on the accuracy of buildup factors used in the calculations. Buildup factors are usually obtained using appropriate computer codes, either based on discrete ordinates transport method or Monte Carlo approach. Since these codes put strong demands on computer resources, they are applied on a limited number of shielding configurations and an attempt is made to use these results and formulate an empirical expression for buildup factors estimation. Due to high physical complexity of neutron transport through shielding material it is very hard to perform parameterisation in order to establish adequate empirical formula. Existing formulas are very limited and are usually applicable to a narrow neutron energy range for few commonly used shielding materials, mostly in monolayer configuration. Recently, a new approach has been proposed for determination of gamma ray buildup factors for mono-layer, as well as multi-layer shielding configurations covering a wide gamma ray energy range. The new regression model is based on support vector machines learning technique, which has theoretical background in statistical learning theory. Development of named regression model required a large number of experimental data obtained by Monte Carlo computer code. More than 7000 Monte Carlo runs were required. Due to physical complexity neutron transport is likely to require even more experimental data in order to generate a model of reasonable accuracy. Therefore, the choice of appropriate Monte Carlo code is a very important question. One has to take into account the accuracy as well as the time required for input preparation and running the code. What also has to be considered is the possibility of the code to be incorporated in an algorithm for automated generation of experimental data. In this paper three Monte Carlo codes are analysed, namely SCALE4.4 code package (SAS3 sequence), SCALE6.0 code package (MAVRIC sequence), and MCNP5. Two simple experimental setups based on a point isotropic source in spherical and slab-like shield are modelled, and the codes are examined on previously mentioned issues. The comparison results show that each one of the examined codes has potential to be used for neutron buildup factor model generation. However, some aspects of their utilization require further analysis prior to final selection

Mechanism of Formation of Monodispersed Colloids by Aggregation of Nanosize Precursors

It has been experimentally established in numerous cases that precipitation of monodispersed colloids from homogeneous solutions is a complex process. Specifically, it was found that in many systems nuclei, produced rapidly in a supersaturated solution, grow to nanosize primary particles (singlets), which then coagulate to form much larger final colloids in a process dominated by irreversible capture of these singlets. This paper describes a kinetic model that explains the formation of dispersions of narrow size distribution in such systems. Numerical simulations of the kinetic equations, with experimental model parameter values, are reported. The model was tested for a system involving formation of uniform spherical gold particles by reduction of auric chloride in aqueous solutions. The calculated average size, the width of the particle size distribution, and the time scale of the process, agreed reasonably well with the experimental values.Comment: 38 pages in plain TeX and 7 JPG figure

Croatian Catholic Movement and the Creation Of The Yugoslav State (1912-1918)

The article is dealing with the activities of the Croatian Catholic Movement during the period from 1912 to 1918. The author focused on the Movement\u27s relation towards the idea and activities that led to the formation of Yugoslavia in 1918

RELIGIOUS COMMUNITIES IN CROATIA FROM 1945 TO 1991: SOCIAL CAUSALITY OF THE DISSENT BETWEEN COMMUNIST AUTHORITIES AND RELIGIOUS COMMUNITIES\u27 LEADERSHIP

The author is dealing with the position of religious communities in Croatia during the period of Communist Yugoslavia. She is focused on permanent conflict between Communist atheist views and religious views of various religious communities in Croatia (primarily of the Catholic Church). Yugoslav Communist authorities did not hesitate to use all means to suppress religion. Therefore numerous clerics were persecuted or maltreated, and religious citizens were often discriminated

Rezension zu: N. Robertson, Religion and reconciliation in Greek cities: the sacred laws of Selinus and Cyrene

Rezension zu: N. Robertson, Religion and reconciliation in Greek cities: the sacred laws of Selinus and Cyrene. APA American classical studies 54 (Oxford/New York 2010