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  • Author: Krzysztof Piotrowski x
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Abstract

The paper presents a description of the development of the human heart based on the present state of knowledge cytogenetics and molecular genetics. Despite the complexity of the genetic mechanisms described, the authors emphasize that it may be just a slice patterns in kardiogenezie. Aberrations and mutations lead to the formation of congenital heart defects in both isolated and components of genetic syndromes.

Size-dependent growth kinetics of vitamin C crystals in water solutions of L(+)-ascorbic acid with the addition of methanol and ethanol

Growth kinetics of vitamin C crystals during the batch mass crystallization process in L(+)-ascorbic acid - methanol - ethanol - water system was determined. The linear growth rate values were estimated on the basis of the product crystal size distributions. The kinetic model of the continuous process in a MSMPR crystallizer was adopted for the batch mode description according to Nyvlt's conception, taking the sizedependent growth (SDG) rate effects into consideration. The kinetic parameter values were determined with a Rojkowski hyperbolic SDG model. A good compatibility between the experimental product crystal population density distributions and the SDG model predictions was observed. The interpretation of the kinetic data was presented and discussed.

Kinetics of the continuous reaction crystallization of barium sulphate in BaCl2 - (NH4)2 SO4 - NaCl - H2O system - neural network model

One of the main toxic components of post quenching salts formed in large quantities during steel hardening processes is BaCl2. This dangerous ingredient can be chemically neutralized after dissolution in water by means of reaction crystallization with solid ammonium sulphate (NH4)2 SO4. The resulting size distribution of the ecologically harmless crystalline product - BaSO4 - is an important criteria deciding about its further applicability. Presence of a second component of binary quenching salt mixture (BaCl2-NaCl) in water solution, NaCl, influences the reaction-crystallization process kinetics affecting the resulting product properties. The experimental 39 input-output data vectors containing the information about the continuous reaction crystallization in BaCl2 - (NH4)2 SO4 - NaCl - H2 O system ([BaCl2]RM = 10-24 mass %, [NaCl]RM = 0-12 mass %, T = 305-348 K and τ = 900-9000 s) created the database for the neural network training and validation. The applicability of diversified network configurations, neuron types and training strategies were verified. An optimal network structure was used for the process modeling.

Abstract

This study is devoted to the analysis of the impact that the basic constituents of ductile iron (carbon and silicon) and spheroidising treatment combined with inoculation exert on the final properties of heavy ductile iron castings. To evaluate the possibility of the application of ductile iron technology in the manufacture of castings for wind power plants, simulations were conducted on cast hubs of the rotor blades for wind turbines. For this type of product, it is necessary to produce castings characterised by a ferritic matrix (over 90% ferrite) and to reduce the amount of pearlite and graphite to a minimum, both of which are considered as the main structural constituents that affect the casting properties. The key guidelines for the manufacture of heavy castings from ductile iron, wind turbines included, were discussed, with particular emphasis placed on the process of spheroidising treatment and inoculation, both of which are aimed at producing in the structure of castings a spheroidal graphite of a size from 5 to 12 mm (class V to VI) and a ferritic structure in an amount exceeding 90%. This article is the result of the work done by Krakodlew S.A to implement research project No. POIG 01.04.00-12-116/12, supported by the National Centre for Research and Development and financed by the European Regional Development Fund, measure 1.4 POIG (Execution of industrial research and development in the company Krakodlew S.A., 2014).

Abstract

Twin gestations are higher risk pregnancies for fetal mortality especially when associated with genetic disorder and congenital heart defect which significantly increases the complication risk in the co-twin including fetal loss, premature delivery, and organ damage. In this report, we present a case of dichorionic twins in 41 years old woman. A trisomy 21 was diagnosed in one twin associated with uncharacteristic congenital heart defect resulting in single twin demise in mid-gestation. The effect of regular care and proper management was delivery of healthy surviving twin.

Reaction crystallization of struvite in a continuous DTM type crystallizer with a compressed air driven jet pump

Experimental tests covering the production of struvite MgNH4PO4·6H2O from water solutions containing 1.0 mass % of phosphate(V) ions using magnesium and ammonium ions in stoichiometric proportions were carried out in a crystallizer of 1.2 dm3 working volume. The process temperature was 298 K. Struvite crystals of mean size L m from ca. 14 to ca. 38 μm were produced depending on the process environment's pH (9-11) and the mean residence time of suspension in a crystallizer, τ (900-3600 s). In such defined process conditions the linear growth rate of struvite crystals changed from 1.45·10-8 m/s (pH 9, τ 900 s) to 2.06·10-9 m/s (pH 11, τ 3600 s) while the nucleation rate from 5.1·107 to 3.2·109 1/(sm3). Crystal product of the most advantageous granular characteristics was produced at pH 9 and the mean residence time 3600 s. Within this product population the largest sizes reached above 200 μm while the number of crystals smaller than 3 mm was kept below 6%.

Abstract

The biogas produced in municipal wastewater-treatment plants (WWTP) should be cleaned before it can be used as a fuel in internal combustion engines. Efficient running of such engines is possible only subject to using high quality biogas and lubricating oil. Otherwise, biogas impurities in course of complex chemical reactions may form deposits on various engine parts as well as seriously contaminate the lubricating oil. In this paper, mineral deposits containing high concentration of bismuth, silicon, sulphur, calcium and zinc are studied. Silicon deposits demonstrating strong friction properties are formed during combustion of volatile silica compounds. As these deposits build up, abrasion problems, ignition failure and even engine failure result. The bismuth containing deposits comes from bearings degradation, zinc and calcium were derived from the additives present in commercially available lubricating oil, while lead, aluminium, copper, nickel, iron and chromium were introduced by engine wear phenomena. The highest bismuth content was located at the engine cylinder heads and the lowest at the exhaust elements, whereas highest calcium content was registered on the pistons. Silicon containing deposits are highest in the exhaust and lowest at the engine head. Zinc deposits are highest at the piston.