Volume 23, No. 4 (2017)

MECHANICAL PROPERTIES AND MICROSTRUCTURES OF REGENERATED CEMENT FROM WASTE CONCRETE

YILENG DU(1*), HONGJUAN ZUO(1)

It has been a long time since humans started using waste materials in engineering applications. This approach not only reduces the yield of waste, while minimizing the costs of disposal but also limit the cost of new materials. In the field of construction, the reuse of waste concretes has been a strong research in recent years. However the processing of the wastes normally involves complicated processing and lab equipment. In this report we crush and dehydrate waste concretes with normal lab facilities and re-make the cement composites. The waste concretes were crushed and dehydrated at two temperatures, 1280 and 1400 ˚C. To balance the concentration of silica and lime, extra lime at 28.5 % and 16 % were added to the waste concretes. The resultant materials were evaluated with respect to the chemical composition, mechanical properties, and microstructures. It is concluded that the material dehydrated at 1400 ˚C and containing 28.5 % lime presents the best mechanical performance. This report presents a simple and inexpensive method to reuse the waste concretes in applications such as pavements.

APPLICATION ON THE WORKPLACES HAZARDS MEASUREMENT IN A BAKERY UNIT

MIRELA PANAINTE-LEHADUS(1*), NARCIS BARSAN(1), OANA IRIMIA(1), CLAUDIA TOMOZEI(1), EMILIAN MOSNEGUTU(1), FLORIN NEDEFF(1)

The workplaces, where human activity takes place, is characterized by some complex factors that can affect the health of employees. These factors (temperature, humidity, noise, vibration, toxic substances, lighting, particulate matter etc.) can also be generalized as dangerous factors or workplaces hazards [1, 2, 3, 4]. In this article are presented some results obtained after workplaces hazards measurements in a production and sales bakery unit for the parameters: O2, SO2, CO, NH3, temperature, humidity, suspension powders, VOC. The values of the measured parameters particulate matter (0.17 mg/m3 - 0.30 mg/m3) respectively volatile organic compounds (0.8 ppm ÷ 21.1 ppm) were below the maximum allowable concentrations, which indicates a safe workplaces for employees. The other parameters measured values, respectively temperature and humidity, were between 22.100C - 29.20 C for temperature and 47% - 53% for humidity.

STUDIES ON CERTAIN GROWTH PARAMETERS OF DIFFERENT PROBIOTIC STRAINS

DUMITRA RĂDUCANU(1), ANA-MARIA GEORGESCU(1*)

The researchers found that probiotics contain microorganisms belonging to genus: Streptococcus, Lactobacillus, Bacillus, Aspergillus, Saccharomyces, Enterococcus, Pediococcus, enzymes (lactoperoxidase, gluconase, nonspecific enzymes) and rumen extracts. In this study, commercial probiotic bacteria known as "Linex" were used as samples. Cultural characteristics of these probiotic bacteria have been isolated and studied. It has been found that solid culture medium (nutritional gelose) favored the growth and development of bifidobacteria better than the liquid nutrient medium (nutrient broth). Thus, the number of bifidobacteria resulting from direct counting with Thoma chamber was of 7890 cells.

NEW TETRANUCLEAR AND MONONUCLEAR OXALATO ORGANOTIN (IV) COMPLEXES WITH MONOCYCLOHEXYLAMMONIUM AS ADVERSE CATION: SYNTHESIS AND INFRARED STUDY

MODOU SARR(1*), AMINATA DIASSE-SARR(1), LIBASSE DIOP(1)

Eight new adducts and derivatives have been synthesized and studied by infrared. Discrete, layered or infinite chain structures are suggested with an oxalate behaving as a monodentate, bidentate, monochelating or bichelating ligand, the environment around the tin centres being tetrahedral, cis trigonal bipyramidal or octahedral. In all the studied compounds, supramolecular architectures may be obtained when intermolecular hydrogen bonds are considered.

NEW TRANS-1,2- CYCLOHEXYLDIAMINO-NN,N’N’ (CH2CO2)(CH2CO2H)3 ANION CONTAINING ADDUCTS AND DERIVATIVES: SYNTHESIS AND INFRARED STUDY

GORGUI AWA SECK(1), ABOUBACRY SENE(1*), LIBASSE DIOP(1)

Five Cyclohexyldiamino-NN, N’N’(CH2CO2)(CH2CO2H)3 anion containing adducts and derivatives with tin, antimony and mercury halides have been synthesized and characterized by infrared spectroscopy. The suggested structures are discrete, the anion behaving as a monodentate or a monochelating ligand: the environments around the metallic centres are trigonal bipyramidal or octahedral.The carboxylic groups and the cation, when involved in extra OH---O, OH----Cl or NH---Cl or O hydrogen bonds may lead to supramolecular architectures.

INDUCED DEGRADATION OF CRUDE OIL POLLUTED SOIL BY MICROBIAL AUGMENTATION

SYLVESTER UWADIAE(1*), EMIKE OMOAYENA(1)

This study was aimed at assessing the effectiveness of indigenous microbes for remediation of hydrocarbon contaminated soil by first increasing the population of the indigenous microbes via bioaugmentation. Soil samples were treated using a consortium of bacteria: Bacillus substilis and Pseudomonas sp. which were isolated and cultured from the contaminated soil. The non-bacteria injected soil sample had the highest hydrocarbon content (THC) of 271.021 in comparison with the other soil samples. The THC percentage removal of B1 (96.885 %), B2 (97.562 %), B3 (98.835 %), B4 (99.594 %) and B5 (99.540 %) were higher than that of the control; indicating that biodegradation actually took place.