The Behavior of Cement-Bonded Particleboard with Modified Composition under Static Load Stress

This article presents research on the behavior of cement-bonded particleboards under mechanical stress caused by the static load. The composition of the boards was modified using alternative raw materials–dust (DU) forming during the processing of cement-fibre boards and particle mixture (PM) generated in the production of cement-bonded particleboards. The particleboards (1-year-old) were subjected to an adverse environment (100 to 250 frost cycles). Mechanical parameters were tested, and the development of defects during static load of the boards by bending was analyzed using acoustic emission. Particleboards with modified compositions are slightly more resistant to adverse environments. The results of the acoustic emission showed the different types of defects occurring under stress by bending. Standard-composition particleboards showed defects located mainly under the cylindrical stress-test head. The modified boards showed larger location distribution of the occurring defects that were also concentrated further away from the cylindrical stress head. The energy during the occurrence of defects was higher in the modified boards in the location of weight application than in the reference boards.

Use of the chemical Fricke dosimeter and its modifications for dosimetry of gamma neutron radiation of a pulsed reactor

The paper investigates the characteristics of the chemical Fricke dosimeter (with the standard composition (D1), without NaCl addition to the solution (D2), without NaCl but with a tenfold increased concentration of Fe2+ (D3)) under continuous and pulsed irradiation with an ultra-high dose rate of the BARS-6 reactor with unshielded metallic cores. The dosimeter radiosensitivity had a linear dependence on the gamma neutron radiation dose in a range of 25 to 750 Gy and was respectively 1.96 ± 0.05 μGy–1 (D1), 2.04 ± 0.05 μGy–1 (D2), and 2.08 ± 0.5 μGy–1 (D3) in the continuous irradiation mode, and 1.24 ± 0.05 μGy–1, 2.00 ± 0.05 μGy–1, and 1.94 ± 0.05 μGy–1 in the pulsed irradiation mode. This makes ≈ 60% of their sensitivity to the 60Со gamma radiation (3.40 ± 0.02 μGy–1), and 36%, 1.6 times as less, for a standard Fricke dosimeter irradiated in the pulsed mode. The experimental value of the radiation chemical yield, Gn(Fe3+), for all solution modifications and both irradiation modes varied slightly and was 0.84 ± 0.11 μM/J on the average, except for the standard solution in the pulsed mode (0.66 ± 0.07 μM/J). The neutron doses determined by chemical and activation dosimeters coincided within the error limits, but the chemical dosimeter readings were systematically higher, by about 20%. Therefore, in the fission spectrum neutron dose rate range of 0.4 to 7×108 Gy/min, there is no dose rate effect both in the standard Fricke dosimeter version (without NaCl) and in the modified version, which makes it possible to use modified Fricke dosimeters to assess the physical and dosimetry characteristics of mixed gamma neutron radiation beams.

Effect of nanostructured Al2O3 on poly(ethylene oxide)-based solid polymer electrolytes

In this study, we investigated the effect of nanostructured Al2O3 particles on Li ion conducting, poly(ethylene oxide) (PEO)-based membranes prepared by electrospinning, solution casting and hot pressing. Pure PEO:LiBF4 solid polymer electrolytes (SPEs) and also plasticizer containing membranes were investigated with various amounts of Al2O3. In a first step, the best-performing composition of pure PEO:LiBF4 concerning the resulting ionic conductivity was identified and used as a standard for further experiments. In the following, the influence of the preparation method, the nature of the Al2O3, and the type of the plasticizer additives on the thermal and electrochemical properties for this standard composition were investigated. The Al2O3 composition was varied between 1 and 5 wt%. The ionic conductivity of bare electrospun PEO:LiBF4 SPE standard material has been improved by a factor ten to 1.9 × 10−6 S cm−1 at T = 293 K when 5 wt% of Al2O3 is added. For solution-casted PEO:LiBF4 standard compositions 18:1 with an initial ionic conductivity of 6.7 × 10−8 S cm−1, the addition of 2 wt% Al2O3 increased the performance to 1.4 × 10−7 S cm−1, both at T = 293 K. If succinonitrile and Al2O3 was admixed to the solution casted standard material, the ionic conductivity was further increased to reach 5.5 × 10−5 S cm−1 at T = 293 K. This material with a composition of 18:3:1 + 2 wt% Al2O3, outperforms the standard material by three orders of magnitude.

Thematization of Lecture Courses: V. Bibikhin's Strategies of Thought

This article is devoted to the main methods of thought that Vladimir Bibikhin uses to form the subject field of his lecture courses. The focus is on four such techniques: the combination of the meanings of everyday language (Aristotelian approach), the clash of extreme positions (dialectics without synthesis), the hermeneutic circle, as well as the boundaries of text collection (Bibikhin's moments of silence). At the very beginning of the article, the author analyzes the most “traditional” lecture courses of Vladimir Bibikhin (such as “Philosophy of Law” and “History of Modern Philosophy”), demonstrating their non-standard composition and thematization. The techniques revealed are the result of the practice of “slow reading” of Bibikhin's lectures. There are four main methods: combining the meanings of everyday language (1), the collision of extreme positions (2), the circular, hermeneutic structure of the lecture (3), the composition of the main blocks of thought in abrupt transitions, in silence (4). Bibikhin seeks to suspend the viewer's desire to “define”, to recognize the familiar in the unfamiliar. At the same time, Bibikhin carefully leads his reader and listener between, on the one hand, the businesslike vanity of thinking and, on the other hand, complete indifference and disinterest. As the main principle for avoiding these extremes, Heidegger's “a priori perfect” is put forward, according to which everything “always has already happened”, and therefore the thought is forced to deal with being late to the event of the world.

IMPROVING THE HARDENABILITY OF MASSIVE FORGINGS FROM ALLOYS OF THE Al–Zn–Mg–Cu SYSTEM BY BALANCED ALLOYING WITH ZINC AND MAGNESIUM

The paper presents the results of studies of the influence of the Zn:Mg ratio on the hardenability, structure and complex of mechanical and corrosive characteristics of forgings with 150 mm thickness made of alloys based on Al–Zn–Mg–Cu system, manufactured in the production conditions of metallurgical plants of JSC AMR and Public Corporation “KUMZ”. It has been determined that an alloy of the Al–Zn–Mg–Cu system with Zn:Mg ratio of not less than 4,1:1 and copper mass content of not more than 1.2% has a higher hardenability compared to the 1933 alloy of standard composition, which ensures homogeneous structure and indicators of mechanical and corrosion properties over the thickness of semi-finished pro-ducts; in metallurgical industry at the stage of manufacturing this allows reducing the residual quenching stresses in massive forgings by means of straightening by reduction in an as-quenched state.

A serine protease secreted from Bacillus subtilis cleaves human plasma transthyretin to generate an amyloidogenic fragment

Aggregation of human wild-type transthyretin (hTTR), a homo-tetrameric plasma protein, leads to acquired senile systemic amyloidosis (SSA), recently recognised as a major cause of cardiomyopathies in 1–3% older adults. Fragmented hTTR is the standard composition of amyloid deposits in SSA, but the protease(s) responsible for amyloidogenic fragments generation in vivo is(are) still elusive. Here, we show that subtilisin secreted from Bacillus subtilis, a gut microbiota commensal bacterium, translocates across a simulated intestinal epithelium and cleaves hTTR both in solution and human plasma, generating the amyloidogenic fragment hTTR(59–127), which is also found in SSA amyloids in vivo. To the best of our knowledge, these findings highlight a novel pathogenic mechanism for SSA whereby increased permeability of the gut mucosa, as often occurs in elderly people, allows subtilisin (and perhaps other yet unidentified bacterial proteases) to reach the bloodstream and trigger generation of hTTR fragments, acting as seeding nuclei for preferential amyloid fibrils deposition in the heart.

ERYTHROCYTE FREEZING DURING THE MODIFICATION IN COMPOSITION OF CRYOCONSERVANT BASED ON GLYCEROL

Damage to red blood cells occurring during freezing can also develop with transfusion. An increase in the concentration of free iron in the blood during the destruction of red blood cells results in an acceleration of the reactive oxygen species production, peroxide damage to cells and stimulation of inflammation. With multiple transfusions of red blood cells, the function of internal organs may be impaired as a result of iron overload. The cryoprotective properties of glycerol include its collegiate ability to reduce the concentration of NaCl at temperatures below 0°C. However, it was found out that the cryoprotective efficacy of glycerol was far less than it was expected from its colligative properties. Damage to red blood cells during their rapid thawing is the result of osmotic shock due to the inability of an excess of intracellular glycerol to exit the cells quickly enough to prevent their swelling and hemolysis. These data indicate the need to reduce the glycerol concentration in the cryoconservant. However, maintaining the protective effectiveness of the cryoprotectant requires a decrease in the NaCl concentration. This study investigates the effect of the composition of the cryoconservant on erythrocyte hemolysis during freezing and hypothermic storage. We used 2 types of cryoconservants: a) 38% (w / v) glycerin, 2.9% sorbitol, 0.63% NaCl (standard composition); b) 28% (w / v) glycerol, 6.8% sorbitol, 0.25% NaCl (modified composition). It was found out that a decrease in the concentration of glycerol and an increase in the concentration of sorbitol leads to a decrease in the erythrocyte hemolysis. The results obtained suggest that a change in the composition of the cryoconservant will reduce osmotic stress during thawing of red blood cells, which, in turn, will reduce their destruction upon transfusion and the likelihood of inflammation.

Composition Identities of Chebyshev Polynomials, via 2 × 2 Matrix Powers

Starting from a representation formula for 2 × 2 non-singular complex matrices in terms of 2nd kind Chebyshev polynomials, a link is observed between the 1st kind Chebyshev polinomials and traces of matrix powers. Then, the standard composition of matrix powers is used in order to derive composition identities of 2nd and 1st kind Chebyshev polynomials. Before concluding the paper, the possibility to extend this procedure to the multivariate Chebyshev and Lucas polynomials is touched on.

Mucosal bacterial vaccines in clinical practice – a novel approach to an old problem?

SUMMARY OBJECTIVES To evaluate the efficacy of mucosal bacterial vaccines (MBV) in reducing the number of exacerbations in patients with chronic respiratory disease. METHODS A prospective cohort study of patients followed at the Pneumology Unit of the University and Hospital Centre of Coimbra, with frequent infectious exacerbations (3 or more) despite the best therapeutic strategies employed. MBV was used as additional therapy. The number of exacerbations 1 year before therapy and 1 year after it were analyzed. RESULTS A sample of 11 individuals, 45.5% male, mean age 62.5 years. Eight patients had non-cystic fibrosis bronchiectasis, 2 COPD (1 on long-term oxygen therapy), and 1 patient with Mounier Kuhn’s syndrome. Three patients were on azithromycin, 1 on inhaled colistin, and 2 on inhaled tobramycin. Out of the 11 patients, one presented complication (fever), which led to a suspension of therapy (excluded from results). Of the 10 patients who completed treatment, 5 had bacterial colonization and were submitted to a custom vaccine. The remaining 6 completed the standard composition. The average of infectious exacerbations in the previous year was 4.3 (0.7 with hospitalization). In the year after therapy, the mean number was 1.5 (0.5 with hospitalization). CONCLUSION The results obtained in this study favor the use of bacterial immunostimulation to reduce the frequency of RRIs in patients with chronic respiratory disease.