Interfacial Polarization and Dielectric Properties of Epoxy/Graphite Flakes Composites

Dielectric properties of composites based on bisphenol-A-epoxy resin loaded with various content of graphite flakes (GF) have been studied. The dielectric permeability, tangent loss and ac conductivity have been examined in wide temperature (170 – 370 K) and frequency (20 Hz – 200 kHz) range. In composites loaded with GF flakes up to 10 wt.%, the dominant conduction mechanism is tunneling of electrons, while loading of 15 wt.% gives rise to electron conduction through direct contacts between fillers. Dielectric properties of composites are largely determined by the nature of the filler/matrix interface, the filler surface area and the inherent conductivity of the fillers. At low electric field frequencies, dominates socalled interfacial (or space charge) polarization due to accumulation of free charges at the interfaces between two phases (filler and matrix), which differ in electrical conductivity.Influence of the filler surface chemistry have been studied for composites loaded with 5 wt.% graphite flakes obtained: (i) under wet milling, without (GF) or with (GF-Tr100x) adding Triton-100x as a surfactant, or (ii) under dry milling in the presence of KOH (GF-KOH). The surface treatment with KOH notable increased dielectric constant of the epoxy/GF-KOH5 composite, keeping low tangent loss, comparable to the counterpart, the epoxy/GF5 composite

Assessment of possible association between rs378854 and prostate cancer risk in the Serbian population

Prostate cancer (PCa) is the second most commonly diagnosed cancer among men worldwide. Despite its high incidence rate, the molecular basis of PCa onset and its progression remains little understood. Genome-wide association studies (GWAS) have greatly contributed to the identification of single nucleotide polymorphisms (SNP) associated with PCa risk. Several GWAS identified 8q24 as one of the most significant PCa-associated regions. The aim of this study was to evaluate the association of SNP rs378854 at 8q24 with PCa risk in the Serbian population. The study population included 261 individuals diagnosed with PCa, 257 individuals diagnosed with benign prostatic hyperplasia (BPH) and 106 healthy controls. Data quality analysis yielded results showing deviations from Hardy-Weinberg equilibrium in groups of PCa patients and BPH patients as well as in the control group. There was no significant association between alleles and genotypes of the genetic variant rs378854 and PCa risk in the Serbian population. [Projekat Ministarstva nauke Republike Srbije, br. 173016

In Vitro and In Vivo Performance of Plum (Prunus domestica L.) Pollen from the Anthers Stored at Distinct Temperatures for Different Periods

A study was conducted to investigate the effect of different storage periods and temperatures on pollen viability in vitro and in vivo in plum genotypes ‘Valerija’, ‘Čačanska Lepotica’ and ‘Valjevka’. In vitro pollen viability was tested at day 0 (fresh dry pollen) and after 3, 6, 9 and 12 months of storage at four different temperatures (4, −20, −80 and −196◦C), and in vivo after 12 months of storage at distinct temperatures. In vitro germination and fluorescein diacetate (FDA) staining methods were used to test pollen viability, while aniline blue staining was used for observing in vivo pollen tube growth. Fresh pollen germination and viability ranged from 42.35 to 63.79% (‘Valjevka’ and ‘Čačanska Lepotica’, respectively) and 54.58 to 62.15%, (‘Valjevka’ and ‘Valerija’, respectively). With storage at 4◦C, pollen viability and germination decreased over the period, with the lowest value after 12 months of storage. Pollen germination and viability for the other storage temperatures (−20, −80 and −196◦C) were higher than 30% by the end of the 12 months. Pollination using pollen stored at 4◦C showed that pollen tube growth mostly ended in the lower part of the style. With the other storage temperatures, pollen tube growth was similar, ranging between 50 and 100% of the pistils with pollen tubes penetrated into the nucellus of the ovule in the genotype ‘Čačanska Lepotica’. The results of these findings will have implications for plum pollen breeding and conservation. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Investigation of S-incompatibility breakdown in 'Karina' sweet cherry

The paper presents results of a two-year study of self-(in)compatibility in 'Karina', previously reported as a self-incompatible sweet cherry cultivar. After emasculation and bagging, pistils of 'Karina' were selfed and pollinated with the nominally cross-incompatible cultivars 'Germersdorfer 1' and 'Lambert' at the beginning of full flowering. In the same way, the pollen of 'Karina' was used to pollinate 'Germersdorfer 1' and 'Lambert'. PCR analysis to determine S-genotypes of 'Karina', 'Germersdorfer 1' and 'Lambert' using consensus and allele-specific primers for S-RNase resulted in patterns consistent with S3S4 genotype. After selfing, 'Karina' behaved as self-compatible, since its pollen tubes reached the base of the style and ovary, penetrating the nucellus and fruit set was recorded in both years. Pollen tubes penetrating the nucellus and fruit set were also recorded after pollination with 'Germersdorfer 1' and 'Lambert'. In contrast, 'Germersdorfer 1' and 'Lambert' did not set any fruit when pollinated with 'Karina'. Microscopic observation showed pollen tubes ending the growth in the upper and middle third of the style. The behaviour of 'Karina' after selfing, as well as its behaviour as the pollen donor/recipient in pollination with cultivars of the same S-allele constitution requires further molecular and genetic analysis

Leaching of copper(I) sulfide in calcium chloride solution

Finely grained samples of copper(I) sulphide were leached by CaCl2·2H2O solution with added HCl and the introduction of gaseous oxygen. The occurrence probability of chemical reactions was analyzed based on literature and products, which were formed during the process, and the overall leaching reaction was defined. The effect of temperature, concentration of CaCl2·2H2O, HCl and total chloride ions, stirring speed, phase ratio and time, on the leaching degree of copper was studied. The quantity of copper dissolved increases with the increase of the values of all the parameters. The role of chloride ions is to disrupt the passivating sulphur layer on the particle surface, by promoting the formation of crystalline sulphur rather than a crypto-crystalline or amorphous product. It was concluded that the leaching reaction is second order, with respect to the concentration of total chloride ions. Experimental results show that the leaching mechanism is very complex. By using appropriate mathematical kinetic models, it is found that the leaching rate is diffusion-controlled

Occurrence of specific behaviour of growing pollen tubes in the ovary of the 'Pozna Plava' plum cultivar

Plum cultivar 'Pozna Plava' was developed at the Fruit Research Institute, Cacak, and released as a new cultivar in 2008. This plum cultivar bears poorly and irregularly, resulting in very low fruit set. Therefore, the occurrence of specific behaviour of growing pollen tubes in the ovary was studied over a three-year period, in three pollination variants (self-, cross- and open). The cross-pollination was performed using the pollen of 'Cacanska Najbolja', 'Hanita' and 'Presenta' plum cultivars. Growth of pollen tubes was observed by means of fluorescent microscopy. The analysis was conducted taking into consideration whether or not the pollen tube has penetrated into the nucellus. Presence of specific behaviour of growing pollen tubes in the ovary was observed in all pollination variants. Atypical pollen tube growth was recorded in the locyle of the ovary as well as in the region of the obturator, the micropyle and the embryo sac. The largest percentage of atypical pollen tube growth in all pollination variants, before and after the penetration into the nucellus was recorded in the obturator and micropyle region. In the open pollination variant, the ovaries showing this specific behaviour of growing pollen tubes, were noted in only one year. Cross- and self-pollination variant showed the existence of specific behaviour of growing pollen tubes in all regions of the ovule, including the embryo sac (except in self-pollination). Only in cross-pollination variant, correlation-regression analysis has shown that specific behaviour of growing pollen tubes did affect the pollen tube penetrating into the nucellus

Fertilization biology of 'Reka' highbush blueberry

The paper presents results of the three-year study of fertilization biology of 'Reka' highbush blueberry (Vaccinium corymbosum L.) under the cross-, open and self-pollination variants. Cross-pollination was performed using the pollen of 'Bluecrop', 'Duke', 'Nui' and 'Ozarkblue'. Pollen tube growth in vivo was monitored using fluorescent microscopy method. The folowing parameters were observed: the average number of pollen tubes in the upper part and base of the style, number of ovary locules with the penetration of pollen tubes, and polen tubes' growth dynamics through certain pistil parts. The highest number of pollen tubes in the upper part and base of the style, as well as the fastest penetration into the ovary locules were found in the open pollination variant. Significant decrease of pollen tubes number from the upper third to the base of the style has been recorded in all pollination variants, whereas in the self-pollination variant it was to the greatest extent. The results also indicated that pollen tube growth dynamics in the progamic phase of fertilization was significantly influenced by pollenizer genotype and environmental factors, temperature in particular. On the second day after pollination, pollen tubes penetrated the ovary locules in all pollination variants, implying that favourable period for fertilization in this cultivar was one to two days after flower opening. In self- and cross-pollination variants, dynamics of pollen tubes growth was similar, indicating that cultivar 'Reka', commonly grown in multi-varietal, could also be grown in mono-varietal plantations (without pollenizers)

Correlation between polymorphisms at promoter region of the NOS3 gene and prostate cancer in Serbian population

Objective: Prostate cancer (PC) is the most common malignant disease in men in the Western Hemisphere. The NOS3 has a role in vascular development, regulation of the vascular tone and tumor growth in PC. In previous studies, the -786 T > C polymorphism was found to be the most important promoter alteration of the NOS3 gene that may affect the PC progression. The purpose of this study was to evaluate 786 T > C, -764A > G, -714 G > T, -690 C > T and -649 G > A polymorphisms in the promoter region of NOS3 gene as genetic indicators of the relative risk of the PC occurrence in Serbian population. Method: In this study, we characterized these polymorphisms by PCR amplification, followed by capillary electrophoresis sequencing in the peripheral blood samples from 50 patients with PC, 50 benign hyperplasia patients and 50 individuals over 40 years of age who showed no clinical signs of any prostatic disease, that were used as controls. Results: Three of the analyzed polymorphisms (-764A > G, -714 G > T and -649 G > A) were not detected during this study. It is interesting to observe that when the -786 T > C polymorphism was present, -690 C > T polymorphism was also found. Conclusion: This study demonstrates no association between the -786 T > C polymorphism in the promoter of the NOS3 gene and the development of PC