Stroboscopic determination of settling velocity, size and porosity of activated sludge flocs

A multi-exposure photographic method was developed for the combined measurement of the settling velocity and size of activated sludge flocs. The proposed method mainly differs from the previous stroboscopic tests by introducing a new experimental arrangement which ensures sharp images of flocs on photographs.The relationships between individual floc-settling velocity and the floc size were found to be linear or fractional power functions. All these relationships were well correlated.Based on a simplified floc structure assumption and results of experimental measurements of floc-settling velocity and size, the floc porosity was determined. The porosity increased at two distinct rates as the floc size increased.     

Sprouted wheat grain with ferritin overexpression as a potential source of iron for cereal product fortification

Grains of winter wheat (Korweta variety) were partially germinated in an abiotic stress condition (0–15 mM FeSO₄ solutions) in order to accumulate iron by ferritin overexpression. The physical, chemical, biochemical properties and technological parameters of the obtained material as well as their resistance to an insect storage pest—granary weevil—were analyzed. Sprouted wheat grains with overexpression of ferritin contain 52 times more iron, more than 50 % in form of ferritin. The contents of reducing sugars, crude protein, fiber and ash as well as amylolytic activity increased significantly in sprouted wheat grain, while starch, fat, wet gluten, falling number and inhibition activity against granary weevil α-amylase decreased. Germinated wheat grain enriched with iron strongly affected granary weevil developmental parameters. Despite the fact that technological parameters of the product were deteriorated, it is worth to consider this material application as an iron supplement for cereal products, when the application of soybean is impossible.     

Confidence intervals in repeated-measures designs: The number of observations principle.

Since the publication of Loftus and Masson’s (1994) method for computing confidence intervals (CIs) in repeated-measures (RM) designs, there has been uncertainty about how to apply it to particular effects in complex factorial designs. Masson and Loftus (2003) proposed that RM CIs for factorial designs be based on number of observations rather than number of participants. However, determining the correct number of observations for a particular effect can be complicated, given the variety of effects occurring in factorial designs. In this paper the authors define a general “number of observations” principle, explain why it obtains, and provide step-by-step instructions for constructing CIs for various effect types. The authors illustrate these procedures with numerical examples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Properties of pore structure of thin-layer external plasters under ageing in simulated environment

The basic and commonly used four types of thin-layer facade plasters on cement and silicate binders were subjected to 400 cycles of accelerated ageing in the simulate chamber. The main attention was focused on the character of pore structure evolution during of ageing process. To reach this objective, examinations of the microstructure by the mercury intrusion method and total porosity by the densitometry method were carried out in time per 100 cycles. During the study, the main emphasis was put on the open porosity and changes of dimensional groups of pores. On the ground of the hysteresis of the mercury pressure by mercury intrusion porosimetry testing, the presence of pores with capillary entrance was suggested. In view of this, the cylindrical and spherical model of porous structure has been defined. The contribution of capillary and spherical pores vary in time together with properties such as: average pore radius, length of cylindrical pores and their tortuosity. The changes of these values confirm that atmospherical ageing influences plasters’ binders in two zones. It appears on the one hand by the decrease of total porosity, length and diameter of capillaries but on the other hand by the increase of open porosity and the decrease of pores’ tortuosity. It indicates the tightening character of the inside pore structure of the examined plasters and at the same time it gives diverse effect in its external zone.     

Synthesis of Ternary Titanium Aluminum Carbides Using Self-Propagating High-Temperature Synthesis Technique

Different ternary carbide phases, namely Ti₃AlC₂, Ti₃AlC, and Ti₂AlC, were successfully synthesized in a self-sustaining regime. Direct reactions among elemental powders of titanium, aluminum, and carbon are strongly exothermic, and the resulting reaction products consist of binary carbides and they are partially molten. The use of TiAl, instead of elemental titanium and aluminum, significantly reduces the combustion temperature. As a result, ternary titanium aluminum carbide phases are formed. In addition, the combustion-synthesized products are not sintered and easy to deagglomerate. Reaction conditions and X-ray diffraction patterns of different ternary phases formed in a self-sustaining regime are presented.     

DOMAIN OF INFLUENCE IN THERMOELASTICITY WITH ONE RELAXATION TIME

A domain-of-influence theorem for an initial-boundary-value problem of thermoelasticity with one relaxation time, proposed by Lord and Schulman, is established. The theorem asserts that for a finite time t > 0 a pair (<φ, ), in which φ and are the thermoelastic potential and temperature, respectively, generates no thermoelastic disturbances outside a bounded domain D_t.     

Hydroprocesssing of light gas oil — rape oil mixtures

Two series of experiments of hydroprocessing of light gas oil - rape oil mixtures were carried out. The reactor feed was composed of raw material: first series — 10 wt.% rape oil and 90 wt.% of diesel oil; second series — 20 wt.% rape oil and 80 wt.% of diesel oil.     

Wideband Low‐Reflection Transmission Lines for Bare Chip on Multilayer PCB

The pad pitch of modern radio frequency integrated circuits is in the order of few tens of micrometers. Connecting a large number of high‐speed I/Os to the outside world with good signal fidelity at low cost is an extremely challenging task. To cope with this requirement, we need reflection‐free transmission lines from an on‐chip pad to on‐board SMA connectors. Such a transmission line is very hard to design due to the difference in on‐chip and on‐board feature size and the requirement for extremely large bandwidth. In this paper, we propose the use of narrow tracks close to chip and wide tracks away from the chip. This narrow‐to‐wide transition in width results in impedance discontinuity. A step change in substrate thickness is utilized to cancel the effect of the width discontinuity, thus achieving a reflection‐free microstrip. To verify the concept, several microstrips were designed on multilayer FR4 PCB without any additional manufacturing steps. The TDR measurements reveal that the impedance variation is less than 3 Ω for a 50 Ω microstrip and S11 better than –9 dB for the frequency range 1 GHz to 6 GHz when the width changes from 165 µm to 940 µm, and substrate thickness changes from 100 µm to 500 µm.