Search

Recycling medium-density fiberboards (MDF) presents notable technological challenges, primarily due to the deteriorated properties of the recycled wood fibers obtained from MDF waste. On the other hand, the enhanced valorization of recycled wood in the manufacturing of wood composites represents a viable approach for implementing the principles of a circular bio-economy in the wood-based panel industry and lowering its carbon footprint. This research aimed to investigate and evaluate the impact of the hydrothermal hydrolysis regime on the physical and mechanical properties of recycled MDF panels (rMDF). The hydrolysis temperature was varied from 121 °C (saturated steam pressure 0.2 MPa) to 134 °C (saturated steam pressure 0.3 MPa), and three hydrolysis durations, i.e., 30, 45, and 60 min, were applied. A control MDF panel, manufactured in laboratory conditions from industrial pulp, was used to perform the comparative analyses. It was observed that the degradation of the rMDF panels occurred when the hydrolysis temperature was increased from 121 °C to 134 °C. The research confirmed the deteriorated physical and mechanical properties of rMDF compared to the panels manufactured from natural wood fibers. Markedly, no significant differences were detected between the density profiles of the rMDF panels and the control boards fabricated from industrial pulp. As a result of the study, it was found that the hydrolysis temperature has a more significant effect than the processing time. It was also established that, in the preliminary preparation of the MDF panels into samples with dimensions similar to those of pulp chips, the optimal hydrolysis regime is at a temperature of 121° C (saturated steam pressure 0.2 MPa) and a time of 30 min.

Unlike the recycling of particleboards, the recycling of medium-density fiberboards (MDF) is not a widespread industrial practice, and currently, most waste MDF panels are landfilled or incinerated after the end of their life cycle. Therefore, it is of great importance to develop cost-effective methods for MDF recycling. The extraction of resins used for bonding the panels, mostly urea–formaldehyde (UF) resins, is carried out mainly with hydrolysis. Hydrothermal hydrolysis is a more environmentally friendly and cheaper recycling technique compared to acid hydrolysis and allows obtaining a high yield of recycled fibers. The aim of this research work was to investigate and evaluate the effect of hydrolysis regime applied on its efficiency and on the properties of the recycled MDF fibers. For this purpose, thermal hydrolysis was carried out in an autoclave with saturated steam as a heat carrier. The main novelty of the research is the preliminary preparation of the recyclable MDF in samples with dimensions close to those of pulp chips. The effect of hydrolysis regime characteristics, i.e., process time and temperature on the properties of recycled MDF wood fibers, was studied. The hydrolysis temperatures used were 121 °C (saturated steam pressure of 0.2 MPa) and 134 °C (saturated steam pressure of 0.3 MPa); for each temperature, three durations were applied—30, 45, and 60 min. After hydrolysis, the resulting fiber fraction was refined using a hammer mill. The fractional and elemental composition of the recycled fibers obtained were evaluated. The hemicellulose content after each hydrolysis treatment was also determined. The chemical oxygen demand (COD) was defined as an indicator of wastewater contamination and as an indirect indicator of the quantitative yield of the process. The results revealed no significant changes in the elemental composition of the recycled fibers, and the hydrolysis regimes used showed no decrease in pentosan content. The recycled MDF fibers exhibited similar fiber morphology and fractional composition, being shorter than fibers from industrial pulp. The increased temperature and time of hydrolysis resulted in a significant increase in COD values. Based on the obtained results, with a view to the slightest contamination of wastewater (as determined by COD), the most promising hydrolysis regime was at a temperature of 121 °C and a time of 30 min. It should be emphasized that for a confirmation of this statement, the properties of MDF panels fabricated with fibers recycled in different regimes should be subsequently investigated.

Summary: Two-partner secretion (TPS) is widespread in the bacterial world. The pore-forming TPS toxin ExlA of Pseudomonas aeruginosa is conserved in pathogenic and environmental Pseudomonas. While P. chlororaphis and P. entomophila displayed ExlA-dependent killing, P. putida did not cause damage to eukaryotic cells. ExlA proteins interacted with epithelial cell membranes; however, only ExlAPch induced the cleavage of the adhesive molecule E-cadherin. ExlA proteins participated in insecticidal activity toward the larvae of Galleria mellonella and the fly Drosophila melanogaster. Evolutionary analyses demonstrated that the differences in the C-terminal domains are partly due to horizontal movements of the operon within the genus Pseudomonas. Reconstruction of the evolutionary history revealed the complex horizontal acquisitions. Together, our results provide evidence that conserved TPS toxins in environmental Pseudomonas play a role in bacteria-insect interactions and discrete differences in CTDs may determine their specificity and mode of action toward eukaryotic cells.

Electrohydrodynamic instabilities were induced in thin water-in-oil emulsion films by application of external DC electric field. The dominant wavelengths of instabilities were measured for constant electric fields of various strengths. The dominant wavelengths agreed reasonably well with theoretical predictions based on a linear stability model. The linear stability model used in this study took into account experimentally measured repulsive disjoining pressure and calculated Maxwell stress. The observation of such instabilities can help to understand the rupture mechanism of emulsion films under the influence of electric field.

An experiment was undertaken studying the effects of genotype, treatment with growth regulators and duration of rooting period on the percentage of rooting and quality of the root system of green cuttings of giant sequoia (Sequoiadendron giganteum (Lindl.) J.Buchh.). Cuttings were taken from 18 ten-year seedlings of 10 species of origin. The duration of rooting period (3 months vs. 5 months) was statistically reliable for root-and callus formation rates. The extension of rooting period for two month affords 57.76% more rooted cuttings. The genotype is the main factor influencing the percentage of rooting, number of roots formed and the length of the main root. Treatment with auxin also increase the percentage of rooting, number of roots formed and the length of the main root. Treatment with 4000 ppm indole butyric acid (IBA) gives good results at the end of the third and fourth month, but a five-month rooting period cuttings treated with 4000 ppm IBA showed the highest percentage of rooting.

The main goal of this study was to investigate the morphological development of the seedlings of Tilia spp. The experiments were carried out with seeds from three Tilia species. The seeds were harvested from trees in the region of Plovdiv on 30, 45, 60, 75 and 90 days after flowering. The seeds were sown in soil bed immediately after collecting. The sprouting percentage and percentage of developed and survived seedlings were recorded. In a 3-4 leaves development stage, the morphological characteristics of root, stem and leaves were determined. The seedlings have only developed from 90 days seeds. The differences between species were observed. The highest stem was measured in Tilia tomentosa Moench. The largest root system was developed in the seedlings of Tilia platyphyllos Scop. The seed propagation of linden is most effective by using 90 day old seeds.

During the past two decades, the unequivocally recommended treatment method of Type 2 diabetes mellitus was insulin administration and intensification in the earliest possible stage of the diagnosis. This approach is not only unfounded but was never scientifically proven. Yet, it has been zealously advocated to medical professionals. In fact, a sound body of evidence disproves this long-standing treatment approach. This method is a cornerstone of, what we now know to be two great illusions of past century, namely, glucocentrism and intensification. Numerous recently published studies provide alarming data regarding serious side effects of blind intensification and insulin overdosing in T2DM. They raise major concerns and call for revision of the traditional approach. Since insulin is an integral and deeply rooted part of the intensification agenda of treating T2DM, it has now suffered a serious drawback. Alternatively, in this review authors present the novel Gravicentric (Energy) concept of T2DM acceptance and therapy. They offer a new classification of anti-diabetes drugs based on their energy effect and present their Gravicentric Algorithm for wide practical utilization. For that reason, the "ELEPHANT" abbreviation was found as a helpful reminder. Viewing T2DM as disease of energy balance together with anti – energy drugs implementation provide medical doctors an unique opportunity to transform T2DM from "slowly – progressive" disease to rapidly reversible condition, which it actually is.

This study was conducted to investigate the effects of IBA, IAA and NAA on rooting power of semi-hardwood cuttings from Tilia. The cuttings were treated with 30, 40, 50 and 60 mg/l IBA, 100, 150, 200 and 250 mg/l IAA, and 20, 30, 40 and 50 mg/l NAA. The results were reported after three months. The following indicators were analyzed: percentage of rooted cuttings (%), number of roots of cutting and the average length of root (cm). The largest number of rooted cuttings was obtained using 40 mg/l IBA for most of the variants. The treatment with 200 mg/l IAA resulted in the roots with the greatest length. The average length of the roots is increased by treatment with 30 mg/l and 40 mg/l NAA. High doses of IBA, IAA, NAA will provide a weak, brittle root system, which reduces the chances of successful adaptation in replanting.

This study was conducted to investigate the effects of different treatment with ultrasound and stratification of Laurocerasus officinalis L. seeds, conducted in greenhouse conditions during the period 2013-2015. The Laurocerasus officinalis L. is a species with an economic importance for the pharmaceutical industry, and it is also often used in ornamental horticulture. The determination of appropriate conditions for propagation by seeds has an effect on the cost of production. The seeds were treated with 0, 5, 10 and 5 min ultrasound and 2 months stratification. The results showed that the percentage of germinated seeds and quality root system are dependent on the exposition time. The largest number of germinated seeds was obtained with ultrasound treatment of 10 min. The stratification resulted in the obtaining of roots with the greatest length. High doses of ultrasound will provide the breaking of seeds and weak, brittle root system, which reduces the chances of successful adaptation in replanting.

Two modifications of the classical one-dimensional logistic map are proposed, which permitted analytical study of the onset of the bifurcation (period doubling) cascade. The modified maps are two-parametric ones. This introduces new features in their behaviour and makes them more flexible. The results can prove to be useful in the ecological (population dynamics) modeling, where the logistic map is a basic model and also in other fields of application.