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1

Morphological variability of otolith organs in three congeneric Pagellus species

Bostanci Derya, Yedier Serdar, Türker Dilek, Işmen Ali

Oceanological and Hydrobiological Studies

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2024

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Vol. 53, No. 1

88--101

EN

Morphological features of sagittal otoliths in Pagellus acarne, P. bogaraveo, and P. erythrinus samples collected from the Aegean Sea were used to assess the variability both between Pagellus species and between otolith pairs employing scanning electron microscopy (SEM) and contour shape analysis. Twenty-one otolith morphological characters were compared in detail using SEM analysis. Twelve of these characters differ between Pagellus species and are suitable for distinguishing between the three congeneric Pagellus species. Wavelet functions of otolith contour shape were compared for six Pagellus groups. The wavelet functions obtained from the contour shape analysis showed high variability in the antero-dorsal, postero-dorsal, and antero-ventral regions of otoliths among the six groups analyzed. The results of principal component analysis (PCA) of the wavelet data provided a clear distinction between the groups under study. Cluster analysis supported the PCA results and basically divided them into two main branches. One of these branches contained only P. erythrinus, while P. acarne and P. bogaraveo were present in the other branch. This is the first study to provide detailed morphological characters and wavelet analysis of left- and right-side otoliths in these three congeneric Pagellus species from the Aegean Sea.

2

Możliwość wykorzystania technik mikroskopowych do oceny przebiegu procesu koagulacji

Turlej Tymoteusz

Przemysł Chemiczny

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2023

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T. 102, nr 11

1228--1231

PL

Przedstawiono wyniki badań dotyczących możliwości wykorzystania technik mikroskopowych do oceny przebiegu procesu koagulacji. Zaproponowano wykorzystanie zautomatyzowanego analizatora wielkości i kształtu ziaren Morphologi 4. Próbki zawiesiny rzecznej zostały poddane analizie, zarówno bez, jak i z dodatkiem koagulantu PAX 16. Przeprowadzono pomiary mikroskopowe za pomocą komórki wet-cell dla obu próbek. Ocena przebiegu procesu koagulacji została przeprowadzona przez porównanie obrazów zawiesiny bez i z dodatkiem koagulantu. Porównanie tych obrazów pozwoliło na ocenę skuteczności procesu koagulacji i zrozumienie wpływu koagulantu na morfologię cząstek. Wyniki tego badania mogą mieć zastosowanie w optymalizacji procesów koagulacji oraz w ocenie jakości wody w różnych zastosowaniach, takich jak uzdatnianie wody pitnej i oczyszczanie ścieków.

EN

Suspended river water samples were coagulated with PAX 16 and then morphol. analyzed using wet-cell microscopic measurements. The effectiveness of the coagulation process was evaluated by comparing images of the suspension without and with the addn. of coagulant. This method can be successfully used to evaluate the optimization of the coagulation process and the selection of coagulant dose.

3

Pickering emulsion polymerization of styrene towards alfa-functionalized polystyrene latex: parameters and process conditions

Tercki Dariusz, Orlińska Beata, Słotwińska Dominika, Sajdak Marcin

Polimery

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2023

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Vol. 68, nr 4

206--214

EN

Polymerization conditions in the Pickering emulsion of colloidal silica-stabilized polystyrene latex were optimized. The influence of process conditions on various parameters, including particle size and distribution was investigated. Monomodal particles distribution was obtained by conducting the process at a temperature of 80°C in a slightly acidic environment (pH = 5), while maintaining fast monomer conversion. It has been shown that the amount of stabilizer used in the polymerization process affects the rate of polymerization, therefore the temperature of the process should be adjusted to the amount of colloidal silica used in the process.

PL

Zoptymalizowano warunki polimeryzacji w emulsji Pickeringa lateksów polistyrenowych stabilizowanych krzemionką koloidalną. Zbadano wpływ warunków procesu na m.in wielkość i rozkład cząstek. Monomodalny rozkład cząstek uzyskano prowadząc proces w temperaturze 80°C w środowisku lekko kwaśnym (pH = 5), przy zachowaniu szybkiej konwersji monomeru. Wykazano, że ilość stabilizatora użytego w procesie polimeryzacji wpływa na szybkość polimeryzacji, dlatego też temperatura procesu powinna być dostosowana do ilości używanej w procesie krzemionki koloidalnej.

4

Morphological asymmetry in two marine fish species Acanthopagrus arabicus (Family: Sparidae) and Planiliza klunzingeri (Family: Mugilidae), collected from brackish and freshwater environments in southern Iraq

Jawad Laith A., Al-Saboonchi Azhar A., Musa Zainab J., Nazal Azhar M., Al-Dirawi Ahmed M. H.

Oceanological and Hydrobiological Studies

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2023

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Vol. 52, No. 2

228--239

EN

Morphological asymmetry was analysed in two marine fish species Acanthopagrus arabicus and Planiliza klunzingeri,in brackish and freshwater habitats in southern Iraq. For bothspecies, specimens from the Shatt al-Arab River and Shatt al-Basrah Canal exhibited greater asymmetry values for snout length. In both locations examined, the levels of asymmetry of the physical traits increased as the fish grew. The high levels of asymmetry in the two fish species may be linked to heavy metal pollutants in the two aquatic environments studied.

5

Investigation of additive manufactured micro-lattice structures for defence applications

Shaik Ameer Malik, Reddy Bobbili Veera Siva, Sastry C. Chandrasekhara, Krishnaiah J., Ramakrishna B.

Materials Science Poland

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2023

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Vol. 41, No. 2

383--400

EN

This study investigates the blast mitigation capabilities of A286 steel micro-lattice structures produced through additive manufacturing. The research explores the effects of different manufacturing conditions, such as stress relief and heat treatment, on the mechanical properties and blast resistance of honeycomb and gyroid lattice structures in correlation with armour steel structures. Comprehensive evaluations, including surface morphology, corrosion resistance, and compressive residual stress analysis, reveal notable findings for micro-lattice structures. Micro-lattice structures demonstrated 57.23% higher corrosion resistance compared to conventional materials, presently available in the form of rolled homogeneous armour, medium hardness armour, and high-nitrogen steel. Additionally, honeycomb lattice structures exhibit compressive residual stresses of up to 581.90 MPa, providing significant advantages in blast mitigation potential. These results underscore the significance of lattice geometry, material microstructure, and residual stress in enhancing blast resistance. The research offers valuable insights into optimizing additive manufactured structures as an alternative modular solution for defence applications.

6

Comparative Anatomical and Morphological Study of Three Populations of Salvia aethiopis L. Growing in the Southern Balkhash Region

Nurmahanova Akmaral, Ibisheva Nazerke, Kurbatova Natalia, Atabayeva Saule, Seilkhan Ainur, Tynybekov Bekzat, Abidkulova Karimi, Childibaeva Assel, Akhmetova Aigul, Sadyrova Gulbanu

Journal of Ecological Engineering

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2023

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Vol. 24, nr 9

27--38

EN

The manuscript presents the results of morpho-anatomical structure of vegetative organs of Salvia aethiopis L. S. aethiopis L. is a promising medicinal plant of flora of Kazakhstan, which is able to grow under certain soil and climatic conditions. According to its anatomical and morphological features, S. aethiopis L. is a drought-resistant plant that does not tolerate excess moisture. The aim of the study was to investigate the morpho-anatomical structure of S.aethiopis L. plants growing in three different populations of the South Balkhash region of the country. As a result of the study of the morpho-anatomical structure of vegetative organs of the studied plants, the following features of xeromorphic structure of S.aethiopis L. were noted: strong pubescence of all above-ground parts of plants by simple, globular and glandular hairs, well expressed cuticle with small spinules, presence of cuticular thickening of guard cells, large number of stomatal apparatus on lower epidermis. A comparative analysis of the structure of plants of three different populations showed that in the stem of plants of population № 1 the primary cortex and the diameter of the central cylinder are more pronounced in comparison with plants growing in populations № 2 and № 3, which is due to the growing conditions of these populations. In plants of population № 1, an increase in the thickness of the leaf blade as well as inclusions of essential oils, which are localized in single or paired essential oil passages, were noted. In plants of populations № 1 and № 2, the more essential oil passages were observed. The studied plants of population № 1 have the most pronounced thickness of the primary bark than plants of populations № 2 and № 3. The revealed changes in the morpho-anatomical structure of plants are associated with the influence of various environmental and anthropogenic factors depending on the location of the studied plants.

7

Study of Si morphology in AlSi21CuNiMg cast alloy using col our and deep etching

Tillová Eva, Chalupová Mária, Kuchariková Lenka, Bonek Mirosław, Uhríčik Milan, Pastierovičová Lucia

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144618

EN

The effect of possible modification and refining effect of Al-Cu-P-based pre-alloy combined with Fe on the microstructure and the silicon morphology change in hypereutectic Al-Si cast alloy was studied. The samples in the as-cast state were observed by optical and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The 3D morphology of both primary and eutectic silicon was observed by using colour and deep etching in detail. The results showed that the AlCu19P1.4 pre-alloy (1.07 wt.%) combined with the addition of Fe (0.02 wt.%) has a significant effect on the change of the amount, size and morphology of primary Si. This is significantly refined and changes the shape from a coarse irregular star-shaped, polyhedral, or plate-like shape to a fine polyhedral shape. The average size of the primary Si is reduced by about of 78 % from 135 μm to 28 μm and the number of primary Si particles increased from 7.4 to 237. No change in the morphology of the eutectic Si was observed; a refinement of the structure from a coarse needle/plate-like to a fine plate-like structure was seen. The depth etching method using HCl was very effective in the study of the 3D silicon morphology observed, which could be observed in detail without the presence of artefacts.

8

Mechanical properties and Mullins effect in rubber reinforced by montmorillonite

Białkowska Anita, Przybyłek Małgorzata, Sola-Wdowska Marta, Masař Milan, Bakar Mohamed

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 5

art. no. e147059

EN

The present work investigated the properties of rubber vulcanizates containing different nanoparticles (Cloisite 20A and Cloisite Na+) and prepared using different sonication amplitudes. The results showed that a maximum improvement in tensile strength of more than 60% over the reference sample was obtained by the nanocomposites containing 2 wt.% Cloisite 20A and 1 wt.% Cloisite Na+ and mixed with a maximum amplitude of 270 µm. The modulus at 300% elongation increased by approximately 18% and 25% with the addition of 2 wt.% Cloisite 20A and 3 wt.% Cloisite Na+, respectively. The shape retention coefficient of rubber samples was not significantly affected by the mixing amplitude, while the values of the softness measured at the highest amplitude (270 µm) were higher compared to those of mixtures homogenized with lower amplitudes. The loading-unloading and loading-reloading processes showed similar trends for all tested nanocomposites. However, they increased with increasing levels of sample stretching but were not significantly affected by filler content at a given elongation. More energy was dissipated during the loading-unloading process than during the loading-reloading. SEM micrographs of rubber samples before and after cycling loading showed rough, stratified, and elongated morphologies. XRD results showed that elastomeric chains were intercalated in the MMT nanosheets, confirming the improvement of mechanical properties. The difference between the hydrophilic pristine nanoclay (Cloisite Na+) and organomodified MMT (Cloisite 20A) was also highlighted, while the peaks of the stretched rubber samples were smaller, regardless of the rubber composition, due most probably to the decrease of interlayer spacing.

9

Flammability and morphology of Agel leaf fibre- epoxy composite modified with carbon powder for fishing boat applications

Kurniasih P., Wirawan W. A., Narto A., Pribadi O. S., Imron N. A., Rachman N. F., Pradipta A.

Archives of Materials Science and Engineering

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2023

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Vol. 122, nr 1

13--21

EN

Purpose: Fibre Reinforced Polymer Composites have been extensively developed to construct fishing vessels. This study reports on the successful development of the Agel Leaf Fibre (ALF)- Epoxy composite reinforced with carbon powder and fabricated using the Vacuum Infusion method. Design/methodology/approach: The composites were prepared by varying the carbon powder filler content at volumes of 0%, 10%, and 30%. The fire resistance of the composites was investigated using a burning test according to ASTM D-3014 standards. The morphology of the composites was observed through SEM analysis and analysed using ImageJ software. Findings: The research findings reveal that adding 30% carbon powder in the HCP composite reduced the burning rate by 42.624 mm/sec and the time to ignition by 17.33 seconds, indicating improved fire resistance properties. The carbon powder inhibited flame propagation and reduced the combustion rate by 0.49%. The SEM examination confirmed that the fibre porosity decreased, resulting in a denser composite with enhanced fibre-matrix adhesion. Therefore, the implementation of fire-resistant composite materials in fishing vessel construction can be realised. Research limitations/implications: The present study primarily examined the immediate effects of carbon powder additions on the morphology of the composites. However, it is crucial to consider these composites’ long-term stability and durability. Future research should investigate the ageing behaviour, considering environmental factors such as humidity, temperature, and UV radiation, to assess their impact on the morphology and flammability resistance of the composites. Additionally, it is essential to acknowledge that other factors, including fibre orientation, fibre length, and matrix properties, can significantly influence the overall performance of the composites. Practical implications: The enhanced flammability resistance of Agel Leaf Fibre-Epoxy composites with carbon powder additions holds significant benefits for fishing boat applications. In marine environments, the risk of fire incidents on fishing boats is high, making materials with good fire resistance highly desirable. Therefore, implementing fire-resistant composite materials in fishing boat construction can be realised to reduce the risk of fire incidents in high-seas fishing vessels. Originality/value: Composites with added carbon powder exhibited smaller flames, slower burning rates, and a lack of significant flame propagation. This suggests that adding carbon powder acts as an oxygen barrier and reduces the availability of fuel within the composite.

10

Wykorzystanie geometrii fraktalnej do opisu składu granulometrycznego i morfologii materiałów drobnouziarnionych

Banaś Marian, Hilger Bartłomiej

Przemysł Chemiczny

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2022

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T. 101, nr 11

1019--1022

PL

Geometria fraktalna jest użytecznym narzędziem wykorzystywanym w wielu dziedzinach nauki i techniki, m.in. w analizie obrazów, analizie danych finansowych, i medycynie. Stosuje się ją również do opisu morfologii fazy stałej, materiałów drobnouziarnionych, które mogą pochodzić z różnych procesów, a przez to charakteryzować się najróżniejszymi kształtami. Celem pracy jest przedstawienie sposobów opisu morfologii materiałów drobnouziarnionych za pomocą geometrii fraktalnej. W pracy zawarto informacje na temat stosowanych rozmiarów zastępczych dla cząstek fazy stałej, a także współczynników kształtów oraz metod opisywania prędkości opadania cząstek takiej fazy w płynie.

EN

Fractal geometry was used to describe the particle morphology, properties and behaviour (falling rate, permeability) in order to precisely define the particle shape in numerical form (fractal dimension). Information on the equivalent diameters of solid particles, shape factors and methods used to describe the free fall velocity of particles in a fluid were presented. The method of numerical detn. of the fractal dimension using the results of measurements obtained from a laser diffractometer was described.

11

Influence of chemical foaming on the structure and selected properties of glass fiber reinforced PA6

Konczal Natalia, Nowinka Bartosz, Bieliński Marek

Polimery

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2022

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Vol. 67, nr 10

475--482

EN

The effect of the chemical foaming on the structure (SEM) and selected properties of glass fi ber (30, 60 wt%) reinforced polyamide 6 (PA 6) was investigated. Density, tensile properties and Charpy impact strength were determined. Hydrocerol ITP 825 was used as a blowing agent in the amount of 2 wt%. The size of the pores and the foaming degree depended on the distance from the injection point. The smallest pore size (64 μm) was observed for 60 wt% glass fiber reinforced PA6.

PL

Zbadano wpływ procesu spieniania chemicznego na strukturę (SEM) oraz wybrane właściwości poliamidu 6 wzmocnionego włóknem szklanym (30, 60 % mas.). Oznaczono gęstość, właściwości mechaniczne przy rozciąganiu i udarność Charpy’ego. Jako porofor stosowano Hydrocerol ITP 825 w ilości 2% mas. Wielkość porów i stopień spieniania zależały od odległości od punku wtryskiwania. Najmniejszą wielkość porów (64 μm) stwierdzono w przypadku poliamidu zawierającego 60% mas. włókna szklanego.

12

The effect of shape and roughness on flotation and aggregation of quartz particles

Guven Onur

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 6

art. no. 154021

EN

A combination of grinding and abrasion processes was applied to control the shape and roughness of quartz particles to investigate their roles in flotation recoveries and aggregation rates at different collector concentrations. The results showed that while the roundness values (Ro) of quartz particles varied in the range of 0.56-0.58 (Ro) at 480 and 1920 sec grinding, the roughness values of particles varied between 3.12-4.02 μm at 60 and 240 min abrasion. The flotation and aggregation tests showed while the flotation recovery increased from 31.3 % to 34.2 % in reverse proportion to their roundness values at 1x10-6 M DAH concentrations, a similar increasing trend from 34.1% to 38.1 % as a function of their roughness value from 3.12 μm to 4.02 μm. On the other hand, in the case of aggregation tests, while the turbidity values decreased from 40.6 NTU to 32.1 NTU at 1x10-6 M DAH concentrations for rounder particles, it was found as 36.2 NTU to 31.8 NTU for rougher ones. The overall results of this study indicated that tuning the morphology of quartz particles may be used to adjust both the flotation and aggregation rate of particles.

13

Idiosyncratic frequency as a measure of derivation vs. inflection

Copot Maria, Mickus Timothee, Bonami Olivier

Journal of Language Modelling

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2022

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Vol. 10, No. 2

193--240

EN

There is ongoing discussion about how to conceptualize the nature of the distinction between inflection and derivation. A common approach relies on qualitative differences in the semantic relationship between inflectionally versus derivationally related words: inflection yields ways to discuss the same concept in different syntactic contexts, while derivation gives rise to words for related concepts. This differential can be expected to manifest in the predictability of word frequency between words that are related derivationally or inflectionally: predicting the token frequency of a word based on information about its base form or about related words should be easier when the two words are in an inflectional relationship, rather than a derivational one. We compare prediction error magnitude for statistical models of token frequency based on distributional and frequency information of inflectionally or derivationally related words in French. The results conform to expectations: it is easier to predict the frequency of a word from properties of an inflectionally related word than from those of a derivationally related word. Prediction error provides a quantitative, continuous method to explore differences between individual processes and differences yielded by employing different predicting information, which in turn can be used to draw conclusions about the nature and manifestation of the inflection–derivation distinction.

14

The Morphological and Physiological Appearance of Two Vegetable Plants Due to Lead Exposure

Lestari Mahayu Woro, Rosyidah Anis

Journal of Ecological Engineering

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2022

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Vol. 23, nr 6

213--222

EN

This research aimed to determine the effect of different concentrations of Lead (Pb) on the morphology of kale and spinach plants. The process involved planting kale and spinach seeds in tubs and transferring them to polybags with planting media in the form of soil and sand at a ratio of 4:1 after strong roots were developed. It is important to note that the media were analyzed to ensure the Pb content in the soil was below the threshold before planting. Pb was later provided 1 week before planting in the form of PbNO3 in the media at a dose of 1 and 2 g/polybag and mixed effectively to ensure even distribution, while the sample used as the control was not given any Pb. The transplanting process was conducted after the plants were 18 days old in the nursery and the initial observations at 9 DAT showed that the kale leaves were darker with a score of 3 than spinach with a score of 1, but the spinach leaves became darker in color with score 3 as the age of the plants increased. Moreover, the kale changed to a lighter color with a score of 2 from the 9th day of observation after transplanting, while spinach requires 15 DAT to become score 2 until the end of the observation. It should be pointed out that both plants showed morphological changes due to the existence of the Pb but their base leaves did not reflect any effect. The kale leaf tip became blunt, while the spinach leaf tip was not affected and both plants were discovered to have longer roots and more root hairs in the control compared to the treatments. Furthermore, the total chlorophyll of spinach in the control was higher than kale but observed to reduce as the concentration of Pb increased in the treatments. The morphology and physiology of spinach and kale plants changed due to the Pb exposure with the spinach was discovered to be more sensitive as indicated by more visible morphological damage to its leaves at the end of the observation. It is possible to use the morphology of spinach and kale to detect Pb-contaminated land.

15

From Descriptive to Accurate Horseshoe Crab Size Variations in Wild Populations

Chan Li Yu, John Akbar, Shahimi Salwa, Meilana Lusita, Lian Chong Ju, Hoe Loh Ing, Ho Wong Chee, Kumaran Jayaraj Vijaya, Pati Siddhartha, Nelson Bryan Raveen

Journal of Ecological Engineering

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2022

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Vol. 23, nr 12

273--284

EN

Horseshoe crabs have survived until Holocene, but their persistence beyond the Anthropocene is challenged by drastic environment changes that entail impoverishments and the resultant unusual growth sizes. Previously, allometry via morphometric ratio was introduced to classify horseshoe crabs into normal-abnormal growth. However, the descriptive size and weight analysis indicated a considerable portion of Tachypleus gigas with normal allometry. This error was caused by the median sorting of values. Therefore, the same data was treated with correlation before generating a linear equation. By being sexual dimorphs, these arthropods actually have gender-specific morphology indicators which could generate a functional allometry. Since the assessed arthropods were mature, the 19 % yield of smaller female T. gigas was possibly due to degradation effects from poor diets or stress. Yet, for this population, an added risk was female-only harvest. Perhaps, close sizing to male counterparts could be perceived a survival strategy by the female T. gigas. More evidence is needed to strengthen this opinion but for now, this assessment method is novel for accurate allometry assessments in the species with sexual dimorphism. Overall, capture fisheries could have negative impacts and when made severe by sex-specific harvest, the unaccounted practices could collapse sustaining populations.

16

Interfacial Structure of Polytrimethylene Terephthalate/Polyethylene Terephthalate Bicomponent Filament

Yang Zhuli, Wang Fumei, Guan Fuwang, Luo Jin, Qiu Yiping, Zhang Chuyang

Fibres & Textiles in Eastern Europe

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2022

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Vol. 30, no. 1 (151)

71--76

EN

The interfacial structure and binding forces of polytrimethylene terephthalate/polyethylene terephthalate filament were investigated through the methods of Carbon-13 nuclear magnetic resonance (13C-NMR), differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and optical microscopy. When two molten polymers met during the spinning process, an interface layer between the PTT and PET components formed and played an important role in binding the two components together. When the blending time was sufficient, an ester-interchange reaction took place with the generation of the copolymer. The PET recrystallisation was observed in the DSC curve under the influence of entangled PTT molecular chains. The morphology of the cross-section and side view proved that the linear boundary line was short and weaker in binding without a chemical bond and molecular diffusion. Side-by-side bi-component fiber and split-type fiber was able to be controllably spun by adjusting the spinning parameters.

17

Mechanical Effects on Different Solid to Liquid Ratio of Geopolymer Filler in Epoxy Resin

Abu Hashim Mohammad Firdaus, Ghazali Che Mohd Ruzaidi, Daud Yusrina Mat, Faris Meor Ahmad, Al Bakri Abdullah Mohd Mustafa, Zainal Farah Farhana, Hasyim Saloma, Lokman Muhammad Taqiyuddin

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

215--220

EN

Geopolymer is formed from the alkali activation of materials rich in Si and Al content with the addition of a silicate solution to enhance the properties of the materials. This paper presents research on the mechanical properties of fly ash-based geopolymer filler in epoxy resin by varying different solid to liquid ratios using sodium hydroxide and sodium silicate as the alkaline activator. However, the common problem observed from the solid to liquid ratio is the influence of curing time and compressive strength of geopolymer to have the best mechanical property. The mix design for geopolymers of solid to liquid ratio is essential in developing the geopolymer’s mechanical strength. A series of epoxy filled with fly ash-based geopolymer materials with different solid to liquid ratio, which is prepared from 0.5 to 2.5 solid to liquid ratio of alkaline activator. The tensile strength and flexural strength of the epoxy filled with fly ash-based geopolymer materials is determined using Universal Testing Machine under tensile and flexural mode. It was found that the optimum solid to liquid ratio is 2.0, with the optimum tensile and flexural strength value. However, both the tensile and flexural properties of epoxy filled with fly ash-based geopolymer suddenly decrease at a 2.5 solid to liquid ratio. The strength is increasing with the increasing solid to liquid ratio sample of geopolymer filler content.

18

Biobased poly(3-hydroxybutyrate acid) composites with addition of aliphatic polyurethane based on polypropylene glycols

Zarzyka Iwona, Czerniecka-Kubicka Anna, Hęclik Karol, Dobrowolski Lucjan, Krzykowska Beata, Białkowska Anita, Bakar Mohamed

Acta of Bioengineering and Biomechanics

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2022

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Vol. 24, no. 1

75--89

EN

Poly(3-hydroxybutyrate) (P3HB) is the most important of the polyhydroxyalkanoates. It is biosynthesized, biodegradable, biocompatible, and shows no cytotoxicity and mutagenicity. P3HB is a natural metabolite in the human body and, therefore, it could replace the synthetic, hard-to-degrade polymers used in the production of implants. However, P3HB is a brittle material with limited thermal stability. Therefore, in order to improve its mechanical properties and processing parameters by separating its melting point and degradation temperature, P3HB-based composites can be produced using, for example, linear aliphatic polyurethanes as modifiers. The aim of the study is a modification of P3HB properties with the use of linear aliphatic polyurethanes synthesized in reaction of hexamethylene diisocyanate (HDI) and polypropylene glycols (PPG) by producing their composites. Prepared biocomposites were tested by the scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TGA). Furthermore, selected mechanical properties were evaluated. It has been confirmed that new biocomposites showed an increase in impact strength, relative strain at break, decrease of hardness and higher degradation temperature compared to the unfilled P3HB. The biocomposites also showed a decrease in the glass transition temperature and the degree of crystallinity. Biocomposites obtained with 10 wt.% polyurethane synthesized with polypropylene glycol having 1000 g · mole–1 and HDI have the best thermal and mechanical properties.

19

The use of modified silica to control the morphology of polyamide 11 and poly(phenylene oxide) blends

Jeziórska Regina, Szadkowska Agnieszka, Studziński Maciej, Żubrowska Magdalena

Polimery

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2021

|

T. 66, nr 7-8

399--410

EN

Silica having amine functional groups (A-SiO2) obtained by the sol-gel process was used to improve compatibility of polyamide 11 and poly(phenylene oxide) (PA11/PPO 80/20) blend via reactive extrusion in a co-rotating twin screw extruder. Amine functional groups of A-SiO2 can react with the carboxyl groups of PA11 to form graft copolymer with PA11 which can efficiently control the phase morphology of the blend. Silica, thanks to the reinforcing effect, significantly increased stiffness of PA11/PPO blend. On the other hand, it greatly improved impact strength and reduced the crystallinity without affecting the crystallization temperature of PA11due to excellent compatibilizing effect. SEM results showed that despite the lower content of PPO, it formed a continuous phase and PA11 – a dispersed. The addition of A-SiO2 changed the morphology from the droplet-matrix to co-continuous with interpenetrating phases. The greatest size-reduction of both phases, reflecting the highest impact toughness, was observed for the content of 3 wt % A-SiO2. With a higher silica loading, phase inversion was observed with the reappearance of the droplet structure, resulting in a slight decrease in impact strength and significant in elongation at break. TGA showed that the composites exhibited better thermal properties as evidenced by the higher initial degradation temperature (Tonset) and the maximum weight loss rate temperature (Tmax).

PL

Otrzymaną w procesie zol-żel krzemionkę zawierającą aminowe grupy funkcyjne (A-SiO2) zastosowano do poprawy kompatybilności mieszaniny poliamidu 11 z poli(tlenkiem fenylenu) (PA11/ PPO 80/20). Proces prowadzono metodą reaktywnego wytłaczania przy użyciu dwuślimakowej wytłaczarki współbieżnej. Aminowe grupy funkcyjne A-SiO2 mogą reagować z grupami karboksylowymi PA11 i tworzyć kopolimery szczepione z PA11, co może skutecznie kontrolować strukturę mieszaniny. Krzemionka, dzięki efektowi wzmacniającemu, znacznie zwiększyła sztywność mieszaniny PA11/PPO. Natomiast, dzięki doskonałemu efektowi kompatybilizacji poprawiła udarność i zmniejszyła stopień krystaliczności mieszaniny bez wpływu na temperaturę krystalizacji PA11. Wyniki SEM wykazały, że pomimo mniejszego udziału, PPO tworzy fazę ciągłą, a PA11 zdyspergowaną. Dodatek krzemionki zmienił strukturę z kropelkowej na ciągłą z wzajemnie przenikającymi się fazami. Przy zawartości 3% mas. A-SiO2 zaobserwowano największe rozdrobnienie obu faz i najwyższą udarność. Przy większej zawartości A-SiO2 nastąpiła inwersja faz z ponownym pojawieniem się struktury kropelkowej, co skutkowało zmniejszeniem udarności i wydłużenia przy zerwaniu. Badania TGA wykazały, że kompozyty charakteryzują się lepszymi właściwościami termicznymi, o czym świadczy wyższa temperatura początku rozkładu i temperatura maksymalnej szybkości rozkładu.

20

A review of research on the Lemanea genus in Serbia

Mitrović Aleksandra B., Đorđević Nevena B., Simić Snežana B.

Oceanological and Hydrobiological Studies

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2021

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Vol. 50, No. 1

47--59

EN

The first data on the Lemanea genus in Serbia come from the late 20th century. Only one species, L. fluviatilis, was reported from 10 localities in Serbian riverine ecosystems between 1991 and 2017. Extensive research on this genus was performed in April–November 2017–2019, surveying 150 localities in 97 upland and mountain rivers. During this study period, the Lemanea genus was recorded at 14 localities in 12 rivers, while it disappeared from five previously reported localities. A total of four taxa were identified: Lemanea fucina, L. rigida, Lemanea sp. and L. fluviatilis. Lemanea fucina and L. rigida were recorded in Serbia for the first time. L. fluviatilis was the most common taxon. Our research confirmed that Lemanea species prefer similar specific environmental conditions. These species were found in temperate, soft or moderately hard, well-oxygenated and weakly alkaline waters, with low, moderate or high conductivity, and in waters with low content of inorganic nutrients. Due to their sensitivity to changes in environmental conditions, Lemanea species are exposed to negative anthropogenic impact leading to the degradation of their habitats. Intensive construction of small hydropower plants has threatened most habitats of the Rhodophyta species in the last few years.