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1

Korozja sitopiaskownika wykonanego ze stali chromowo-niklowej

Lochyński Paweł, Domańska Magdalena, Kasprzyk Krzysztof

Ochrona przed Korozją

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2019

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nr 7

225--235

PL

Austenityczne stale chromowo-niklowe 304 (1.4301) i 304L (1.4306 oraz 1.4307) od wielu lat są wykorzystywane do budowy urządzeń technologicznych instalowanych na oczyszczalniach ścieków, przepompowniach i zakładach uzdatniania wody. Stale te mogą ulegać korozji w środowisku wodnym z dużą zawartością siarkowodoru oraz okresowo podwyższoną zawartością chlorków. Przykładem szybko postępujących zniszczeń jest opisana w pracy korozja sitopiaskownika, który po 2 latach eksploatacji odznaczał się perforacjami na pokrywach oraz w górnej części ponad poziomem ścieków. Przeprowadzone badania mikroskopowe potwierdziły obecność żywych komórek bakterii i grzybów na ściankach sitopiaskownika. Metoda fluorescencyjnej hybrydyzacji in situ (FISH) wykazała obecność bakterii z klasy γ- i δ-proteobacteria oraz bakterii siarkowych (Acidithiobacillus thiooxidans) należących do klasy γ-proteobacteria. Badania wskazały, że największa intensywność korozji miała miejsce w częściach sitopiaskownika narażonych na działanie wilgotnego powietrza zanieczyszczonego siarkowodorem.

EN

Austenitic chromium-nickel steels 304 (1.4301) and 304L (1.4306 and 1.4307) have been used for many years to build technological devices in water and sewage treatment plants or pumping stations. These steels can be corrosive in aqueous environments with a high content of hydrogen sulphide and periodically increased chloride concentrations. The paper describes an example of fast-progressing corrosive damage of a screenings and grit separator, which after 2 years of operation perforations on the covers and in the part of wall above the sewage level. Microscopic observations confirmed the presence of living cells of bacteria and fungi on the walls of the screenings and grit separator. The fluorescent in situ hybridization (FISH) method showed the presence of sulfur bacteria (Acidithiobacillus thiooxidans) and bacteriafrom the γ- and δ-proteobacteria class. Studies have shown that the highest intensity of corrosion occurred in the parts of the screenings and grit separator exposed to humid air contaminated with hydrogen sulphide.

2

Efficiency of municipal wastewater treatment with membrane bioreactor

Domańska Magdalena, Boral Anna, Hamal Kamila, Kuśnierz Magdalena, Łomotowski Janusz, Płaza-Ożóg Paulina

Journal of Water and Land Development

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2019

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no. 41

47--54

EN

The increasingly stringent requirements for wastewater treatment enforce the adoption of technologies that reduce pollution and minimize waste production. By combining the typical activated sludge process with membrane filtration, biological membrane reactors (MBR) offer great technological potential in this respect. The paper presents the principles and effectiveness of using an MBR at the Głogów Małopolski operation. Physicochemical tests of raw and treated wastewater as well as microscopic analyses with the use of the FISH (fluorescence in situ hybridization) method were carried out. Moreover, the level of electric energy consumption during the operation of the wastewater treatment plant and problems related to fouling were also discussed. A wastewater quality analysis confirmed the high efficiency of removing organic impurities (on average 96% in case of BOD5 and 94% in case of COD) and suspension (on average 93%).

PL

Wraz ze wzrostem wymagań stawianym ściekom oczyszczonym wdrażane są technologie umożliwiające dużą redukcję zanieczyszczeń i jednocześnie małą produkcję odpadów. Biologiczne reaktory membranowe (MBR) dzięki połączeniu klasycznego procesu osadu czynnego z membranową filtracją ścieków stwarzają duże możliwości technologiczne. W pracy przedstawiono zasadę działania oczyszczalni pracującej w Głogowie Małopolskim oraz efektywność jej działania. Wykonano analizę fizykochemiczną ścieków surowych i oczyszczonych oraz analizę mikroskopową z wykorzystaniem metody FISH (fluorescence in situ hybridization), a także przedstawiono poziom zużycia energii elektrycznej podczas pracy oczyszczalni oraz omówiono problemy związane z zarastaniem membran. Analiza jakości ścieków potwierdziła wysoką skuteczność usuwania zanieczyszczeń organicznych (średnio 96% w przypadku BZT5 i 94% w przypadku ChZT) oraz zawiesiny (średnio 93%).

3

Przyczyny korozji stali nierdzewnej w obiektach kanalizacyjnych

Lochyński P., Domańska M., Łomotowski J.

Instal

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2018

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nr 7/8

46--50

PL

Korozja stali znacznie podnosi koszty eksploatacyjne urządzeń narażonych na kontakt z agresywnym środowiskiem w obiektach kanalizacyjnych. Z tego powodu urządzenia technologiczne wykonuje się z materiałów o podwyższonej odporności na korozję, w tym ze stali nierdzewnych. W artykule przedstawiono najczęściej stosowane typy stali nierdzewnej oraz przyczyny powstawania korozji elektrochemicznej i biologicznej pod wpływem ścieków i powietrza o zwiększonej zawartości siarkowodoru. Przedstawiono oryginalne wyniki badań obrazujące zmiany stali chromowo-niklowej wywołane korozją fizykochemiczną i biochemiczną. W badaniach produktów korozji wykorzystano metody SEM/EDS oraz XRD (X-ray Diffraction), a do identyfikacji mikroorganizmów biorących udział w korozji biologicznej zastosowano metody fluoroscencyjne: DAPI, Live/DEAD i FISH (fluorescence in situ hybridization). Analizy wykazały, że zawartość m.in. siarki, siarczków żelaza oraz niklu w produktach korozji stali wskazuje na obecność silnego oddziaływania gazowego siarkowodoru. Badania potwierdziły obecność bakterii siarkowych z gatunku Acidithiobacillus thiooxidans.

EN

Steel corrosion significantly increases the operating costs of equipment that is exposed to the aggressive environment in sewerage objects. Due to that, technological equipment is produced from materials with improved corrosion resistance, including stainless steel. The paper presents the most commonly used types of stainless steel and the reasons for electrochemical and biological corrosion resulting from exposure to air with increased content of hydrogen sulphide. The authors presented the original test results that illustrate the changes in chromium-nickel steel caused by physical, chemical and biochemical corrosion. The corrosion products were analysed with use of the SEM/EDS and XRD (X-ray Diffraction) methods, while microorganisms participating in biological corrosion were identified with use of the following fluorescence methods: DAPI, Live/DEAD and FISH (fluorescence in situ hybridization). The analyses have demonstrated that the content of sulphur, iron sulphide and nickel in the steel corrosion products proves the existence of a strong influence of gaseous hydrogen sulphide. The tests confirmed the presence of sulphur bacteria Acidithiobacillus thiooxidans.

4

Research on the cultivation of nitrifying bacteria and possibility of the biomass storage

Domańska M., Hamala K., Frąszczak M., Łomotowski J.

Architecture Civil Engineering Environment

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2016

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Vol. 9, no. 1

113--118

EN

The efficiency of nitrification has a great influence on the effect of removing nitrogen from wastewater. Problems with the process are associated with reducing the age of activated sludge, lower temperatures of wastewater in aeration chambers, rapid changes in the amount and composition of wastewater containing toxic substances or inhibiting the oxidation of ammonia nitrogen. The research concerned the possibility of cultivation and storage of the nitrifying bacteria biomass, which could be added to the activated sludge in case of a drop of nitrification efficiency. The study showed that even a fouryear- old storage of nitrifying bacteria does not result in their complete destruction.

PL

Sprawność procesu nitryfikacji ma duże znaczenie dla efektu usuwania związków azotu ze ścieków. Problemy z prawidłowym przebiegiem nitryfikacji podczas oczyszczania ścieków pojawiają się przy skróceniu wieku osadu czynnego, niskich temperaturach ścieków w komorach napowietrzania, gwałtownych zmianach składu i ilości ścieków dopływających do oczyszczalni oraz dopływem ścieków zawierających substancje toksyczne lub inhibitujące proces utleniania azotu amonowego. Podjęto badania nad sprawdzeniem możliwości hodowli i przechowywania biomasy bakterii nitryfikacyjnych, którą można byłoby dodawać do osadu czynnego w sytuacjach spadku sprawności nitryfikacji. Przeprowadzone badania wykazały, że nawet 4-letni okres przechowywania bakterii nitryfikacyjnych nie powoduje ich zaniku.

5

Nowoczesne techniki i technologie inżynierii środowiska

Miksch K., Cema G., Felis E., Sochacki A.

Rocznik Ochrona Środowiska

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2015

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Tom 17, cz. 1

833--857

EN

The novel technologies used in environmental engineering were discussed in this paper – the formation of aerobic granules, the Anammox process, the advanced oxidation processes, the use of fungi for dyes decolorization, constructed wetlands, the soil phytoremediation supported by rhizosphere microorganisms and the use of molecular biology technique in environmental engineering. The structure of granular sludge is influenced by EPS production. The average diameter and density of biogranules increase due to EPS production. Although polysaccharides are essential, proteins were found to be the predominant component of aerobic granular sludge. Compared to loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS) showed more significant correlations with granules formation. This investigation will contribute towards a better understanding of the behavior and composition of EPS in sequencing batch reactors. The traditional nitrification and denitrification processes proceed well with typical municipal wastewater. Nevertheless, there are also nitrogen-rich wastewater streams like landfill leachate or reject waters from dewatering of digested sludge, for which traditional nitrification/denitrification can be generally ineffective due to free ammonia inhibition of nitrification and unfavorable biodegradable carbon content for denitrification. Because of high requirements for oxygen and the necessity for addition of external carbon source, treating such nitrogen-rich streams with nitrification/denitrification would become expensive and unsustainable. The least resources consuming pathway for the conversion of ammonium to nitrogen gas is a combination of partial nitrification and the Anammox process. The main advantages of this process compared to the conventional nitrification/denitrification are: low sludge production, decrease of the aeration costs by almost 60% (only half of the ammonia is oxidized to nitrite in the nitritation process without further oxidation to nitrate), and no need for external organic carbon source addition (Anammox process). Furthermore, anammox bacteria oxidize ammonium under anoxic conditions with nitrite as the electron acceptor, and converse energy for CO2 fixation. Additionally, the biomass yield of the Anammox process is very low (0.08 kg VSS kg NH4-N-1 in comparison to 1 kg VSS kg NH4-N-1 in conventional nitrification/denitrification process) consequently, little sludge is produced. The low sludge production is another factor that contributes to the substantially lower operation costs compared to conventional denitrification systems. Advanced oxidation processes (AOPs) are oxidative methods which are based on the generation of the hydroxyl radicals, which are very reactive and less selective than other oxidants. In the wastewater treatment technology, AOPs can be used in a combination with conventional biological techniques (so called hybrid processes), as pre- and post- treatment processes. The advanced oxidation processes have been used in order to increase the biodegradability and also detoxification of the wastewater. The ability of fungi to degrade lignin-cellulose debris is well known. In addition to these natural molecules they may also degrade synthetic compounds, including synthetic dyes. High effectiveness of Evans blue and brilliant green mixture removal by all tested strains was demonstrated. The process was the most effective and fast in shaken conditions. Finally strain MB removed 90% of tested mixture in shaken samples after 96h. It was the best result reached among all the strains used in the experiment. High removal efficiency was accompanied by a decrease of toxicity (from V class to III class in test with D. magna and from IV class even to non-toxic in test with L. minor). The highest decrease of phytotoxicity was noticed in samples with shaken biomass in which the effect of dyes mixture elimination was the best. The research indicates very high potential of tested strains for decolorization and detoxification of dyes mixture. Constructed wetlands are man-made system mimicking the process occurring in natural wetlands. These systems are considered to be an alternative to more technically advanced waste water treatment technologies. The development of constructed wetlands is envisaged to pursue the following directions grouped according to: the type of the waste water to be treated, target contaminants, treatment intensification methods, ancillary benefits and the locality. Mycorrhiza fungi can be used for phytoremediation proccess. They support plant growth by lowering the stress caused by the lack of phosphorus and water. They produce enzymes participating in several stages of xenobiotics decomposition, which is helpful in their further biodegradation performed by the other rhisospherical organisms. The natural colonisation of PAHs contaminated soil is a long-term process. It could be shortend by adding fungal propagules as an inoculum to the soil. Fungi used for the injections should be isolated from PAHs contaminated soil. That guarantees their survival and development in the contaminated environment. The level of PAHs elimination from soil depends on a type of bioremediation modification used. It was shown that the best results are obtained with monocotylous plants combined with bacterial and fungal biopreparations obtained from contaminated soil. The symbiosis of mycorrhiza fungi with monocotylous plants caused ca. 40% increase of 3, 4, 5 and 30% of 6-ring hydrocarbons removal from soil in comparison with the conventional methods. Important aspect of environmental protection and engineering is the possibility for qualitative and quantitative monitoring of complex microbial communities, responsible for biotechnological processes, such as: soil bioremediation, wastewater treatment or composting. Due to the fact that most of the environmental bacteria cannot be grown in the laboratory conditions molecular techniques are widely used in environmental engineering. Among these methods the Polymerase Chain Reaction (PCR)-based and hybridization-based (such as Fluorescent in situ Hybridization; FISH) techniques are known to be the most useful.

6

Differences in populations of filamentous bacteria involved in foaming and bulking of activated sludge

Miłobędzka A., Muszyński A.

Challenges of Modern Technology

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2015

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Vol. 6, no. 3

30-33

EN

Bulking and foaming of activated sludge are related to excessive proliferation of a specific group of activated sludge biocenosis – filamentous bacteria. The research was carried out to compare filamentous bacteria populations in foam and activated sludge in a full-scale municipal wastewater treatment plant located near Warsaw (Poland). Fluorescent in situ hybridization (FISH) – a quantitative, culture-independent, molecular method was applied to evaluate the structure of filamentous populations. Activated sludge and foam were examined for the abundance of eleven groups of these microorganisms, which occur in wastewater treatment plants in Europe. Filamentous bacteria constituted 18% and 24% of all bacteria detected in sludge and foam, respectively. The structures of filamentous bacteria populations in sludge and foam were different, although the same bacteria were found in both types of samples. The most abundant filaments belonged to phylum Chloroflexi (targeted by the CFXmix probe) and genus Microthrix (targeted by the MPAmix probe) in sludge and foam, respectively. The third significantly abundant bacteria was Haliscomenobacter hydrossis (targeted by HHY654).

7

Bakterie nitkowate w osadzie czynnym - przegląd morfotypów, wyznaczniki morfologiczne i molekularne

Miłobędzka A., Muszyński A.

Prace Naukowe Politechniki Warszawskiej. Inżynieria Środowiska

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2014

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z. 68

73--92

PL

Bakterie nitkowate w osadzie czynnym tworzą szkielet kłaczków i rozkładają polimery zawarte w ściekach. Przy ich nadmiernym wzroście zmienia się struktura kłaczków i pojawiają się problemy eksploatacyjne - pienienie i pęcznienie osadu. Skuteczne zwalczanie tych zjawisk jest łatwiejsze, gdy uda się zidentyfikować organizmy za nie odpowiedzialne. Klasyczna analiza mikroskopowa pozwala określić jedynie morfotyp bakterii nitkowatych. Metoda ta jest niedoskonała, gdyż dany morfotyp może obejmować kilka typów filogenetycznych o różnych właściwościach ekofizjologicznych, co utrudnia zwalczanie bakterii odpowiedzialnych za pęcznienie osadu. W celu właściwej identyfikacji należy wykorzystać techniki biologii molekularnej, jak np. metodę fluorescencyjnej hybrydyzacji in situ (FISH).

EN

Filamentous bacteria form the backbone of flocs in activated sludge and decompose polymers in wastewater. Their excessive growth results in changes in the structure of the flocs and operational problems - bulking and foaming. The effective control of these phenomena requires a reliable identification of microorganisms causing these problems. Conventional microscopic analysis of activated sludge leads only to a morphotype classification. This method is not perfect because a morphotype may include several phylogenetic ecotypes with different ecophysiological properties. Therefore, the control of bacteria growth responsible for sludge bulking is difficult. Molecular biology techniques, e.g. the method of fluorescence in-situ hybridisation (FISH), should be used for reliable identification.

8

Automated blurred image region classification

Bera A., Sacharski B ., Sychel D.

Journal of Theoretical and Applied Computer Science

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2014

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Vol. 8, nr 2

37--47

EN

In this paper authors present a simple method for recognizing blurred regions in the image. Proposed algorithm is based on 81 simple features — moments of histogram of image subbands, that were obtained during image decomposition, and ratio derived from gray level co-occurrence matrix (GLCM) are used. The method is compared with a different method, that is based on approaches found in literature. To increase the efficiency of algorithms, authors combined three solutions (edge-detection, gray level co-occurrence matrix and fast image sharpness). The aim of the research was to verify whether it is possible to use simpler methods of feature extraction to achieve similar, or even better, results.

9

A brief overview of the applicability of FISH methods in environmental engineering

Piórczyk J., Jasionowski B., Stańczyk E.

Structure and Environment

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2013

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Vol. 5, no. 1

42--45

EN

Fluorescent in situ hybridization (FISH) is a commonly used method for the detection of microorganisms in heterogeneous environment. It is primarily used for quantitative analysis of microorganisms. FISH gives possibilities of evaluating activities of some bacteria and their physiological state in the environment. In the recent years, ftuorescent in situ hybridization has been improved and adapted for the research on environmental samples.

10

Nowoczesne metody badania bioróżnorodności biocenoz bakteryjnych w środowisku

Karło A., Ziembińska A.

Chemik

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2013

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Vol. 67, nr 11

1105--1114

PL

W analizach biocenoz bakteryjnych coraz powszechniej wykorzystywane są techniki biologii molekularnej. Wśród nich można wyróżnić metodę FISH – fluorescencyjnej hybrydyzacji in situ oraz jej modyfikacje (RING-FISH, Clone-FISH, CARDFISH i MAR-FISH). W artykule opisano też technikę elektroforezy w gradiencie denaturacji (DGGE), bazującą na bakteryjnym markerze molekularnym 16S rRNA oraz cystometrię przepływową. Ze względu na dużą przewagę tych metod nad klasycznymi metodami mikrobiologicznymi, wynikającą między innymi z możliwości analizowania próbek pobieranych bezpośrednio ze środowiska, są one stosowane w biotechnologii środowiskowej, np. w badaniach bakteryjnej biocenozy osadu czynnego, biorącej udział w biologicznym oczyszczaniu ścieków. Możliwe jest również użycie kilku metod, których rezultaty są komplementarne i pozwalają na stworzenie całościowego obrazu badanej biocenozy.

EN

Molecular techniques are very popular in microbial laboratories. Among them FISH- fluorescent in situ hybridization (with modifications like: CARD-FISH, MAR-FISH, RING-FISH, Clone- FISH), DGGE – denaturing gradient gel electrophoresis based on 16S rRNA molecular marker and flow cytometry, are the most popular. These analytical methods are commonly use in bacterial biodiversity research. The analysis can be performed directly on the environmental sample, so these procedures are simpler and faster that traditional ones. Therefore, molecular techniques can be used in aqueous bacterial biocenosis research, such as activated sludge, which takes part in biological wastewater treatment. It is also possible to use a set of molecular methods in order to obtain complimentary results to present total bacterial biocenosis picture.

11

Alternative colour space construction of the stain reaction in FISH image analysis for quantification of the HER2 gene amplification

Markiewicz T., Cichowicz M.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 3a

10-12

EN

The paper presents a study of the different colour representation (intensity of the stain reaction) in FISH images. The better colour visualisation of the centromers and HER2 genes in these methods of the breast cancer stain has a significant influence to correct evaluation of the presence/absence HER2 gene amplification. We taken into account wide range of the image colour representation and propose alternative colour space construction, based on the selected signals in FISH image registration. The proposed approach offers the reduction of the angle between HER2 dots from about 10° to 5.5°.

PL

Artykuł prezentuje analizę różnych reprezentacji barwnych obrazów FISH. Lepsza wizualizacja barwna centromerów i genów HER2 w rozważanym barwieniu preparatów raka sutka ma znaczący wpływ na prawidłowość oceny obecności bądź braku amplifikacji tego genu. W badaniu przeanalizowano wiele reprezentacji barw oraz zaproponowano alternatywny sposób konstrukcji przestrzeni barw, poprzez użycie wybranych sygnałów z rejestracji obrazów FISH. Zaproponowane podejście pozwala zmniejszyć kąt przestrzenny pomiędzy poszczególnymi znacznikami genów HER2 z wartości około 10° do 5.5°.

12

Techniki FISH i PCR w badaniach bakterii akumulujących polifosforany

Muszyński A., Mielczarek A. T., Nielsen P. H.

Gaz, Woda i Technika Sanitarna

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2011

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Nr 5

189-193

PL

Identyfikacja PAO występujących w próbkach osadu czynnego pobranych z dwóch duńskich oczyszczalni ścieków. Zbadano strukturę populacji Candidatus Accumulibacter phosphatis na podstawie filogenetycznej analizy genu kinazy polifosforanowej.

EN

Polyphosphate accumulating organisms (PAOs) are the group of microorganisms primarily responsible for effective phosphorus removal from wastewater. Samples of activated sludge from two Danish full scale wastewater treatment plants (WWTPs) were analyzed for their populations of PAOs using Fluorescence In Situ Hybridization (FISH) and Polymerase Chain Reaction (PCR). The investigations showed that PAOs may account for up to 20% of the community biomass in full scale WWTPs. Among two bacterial groups tested, Tetrasphaera turned out to be the dominant PAO in both plants and constituted about 15% of all bacteria in activated sludge.

13

Phylogenetic diversity and abundance of bacteria from surface microlayer and subsurface water in eutrophic lake

Walczak M., Swiontek Brzezinska M.

Polish Journal of Ecology

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2010

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Vol. 58, nr 1

177-186

EN

The bacteria from different phylogenetic groups were studied in surface microlayer (SM, up to 100 [mu]m ) versus subsurface water (SW - 20 cm) in eutrophic lake from spring to autumn of 2007. Abundance of bacteria was determined using a combination of direct counting of 4', 6-diamidino-2-phenylindole and the phylogenetic diversity was determined in fluorescence in situ hybridization (FISH) method with group-specific, fluorescently labeled oligonucleotide probes. The numbers of DAPI bacteria varied between 4.75 and fluorescence in situ hybridization (FISH) demonstrated that Eubacteria constituted the majority of the whole bacterial population and their percentage share ranged from 59 to 75%. Abundances of alpha- beta-Proteobacteria and Cytophaga-Flavobacteria groups varied across seasons, layers, and lacustrine zones. The lowest number of alpha-Proteobacteria group bacteria was observed in spring (SM - 0.2 x 10[^6], SW - 0.16 x 10[^6] cells cm[^-3]), whereas the highest in autumn (SM - 0.62 x 10[^6], SW - 1.6 x 10[^6] cells cm[^-3]). The percentage share of these groups of bacteria in the Eubacteria domain was lower in spring (20.50%) than in summer and autumn (from 65 to over 80%). No fixed difference between the composition of SM and SW bacteria was noticed. Seasonally occurred changes are similar in both layers.

14

Efficiency of a 252Cf source in normal or in B-10 enriched lymphocytes evaluated by SCGE assay, classical cytogenetics and FISH technique

Cebulska-Wasilewska A., Niedźwiedź W., Florjan D., Schneider K., Kopec M., Kreft A.

Nukleonika

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2001

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Vol. 46, nr 2

41-49

EN

Biological effectiveness of a californium-252 source was evaluated after irradiations in vitro of normal or pretreated cells with compound enriched in the B-10 ion (Na210B12H11SH also known as BSH) in order to check the possibility of any enhancement effect due to the process of boron neutron capture. Peripheral blood lymphocytes were used as a model for human cells. Human blood samples or isolated lymphocytes were irradiated with the isotopic source of 252Cf, at the Faculty of Physics and Nuclear Techniques at the University of Mining and Metallurgy, Kraków, (both the neutron source and the samples were placed in an "infinite" polyethylene block). DNA and chromosomal damage were studied to compare the biological effectiveness of irradiation. Single cell gel electrophoresis also known as the Comet assay was done to investigate the DNA damage. Classical cytogenetic analysis was applied to assess the frequencies of unstable aberrations (dicentrics, rings and acentric fragments). To evaluate the frequencies of stable aberrations the fluorescence in situ hybridisation (FISH) with probes for chromosomes 1, 4 (14,3% of the whole genome) was performed. Linear (or close to linear) increases with radiation doses were observed for the DNA damage and aberration frequencies in lymphocytes both untreated or pretreated with BSH. Levels of translocations evaluated for the whole genome were comparable with the frequencies of dicentrics and rings. No significant differences were detected due to radiation dose in the frequencies of sister chromatid exchanges (SCE) detected in the second mitosis. Statistically no significant differences were observed in various biological end-points between normal or boron pre-treated cells.