Effect of storage conditions on lignocellulose biofuels properties.

This article examines the effects of different storage conditions on selected physicochemical properties of three types of agro-biomass pellets: sunflower husks, wheat straw and hemp hurds, and wood pellets. The tests were carried out in a climatic chamber, which allows simulation of real storage conditions, i.e. conditions with high air humidity and variable (±) ambient air temperatures. The results showed higher degradability of agro-biomass pellets compared to woody biomass. The pellets degraded to a less extent at varying ± temperatures than at high humidity (90% RH). After complete moisture saturation, durability decreases for agro-pellets by an average of 9%, while after freezing and defreezing for sunflower husk pellets and woody pellets durability decreases by 2%, and for hemp hurd pellets by 11%. In contrast, strength-by-dropping index for agro-pellets decreased by 20% after being in the environment (30 °C and 90%RH) and 15% under varying temperature conditions. No change in the energy parameters of all pellets in the dry matter was noted. On the other hand, an increase in the moisture content of pellets when they are stored under different environmental conditions results in a decrease in calorific value.

Resistance to High-Temperature Oxidation of Ti-Al-Nb Alloys.

The research presented in this paper concerns the assessment of the resistance to high-temperature oxidation behaviour of a Ti-46Al-7Nb-0.7Cr-0.1Si-0.2Ni alloy and the explanation of the role of niobium during oxidation processes. The basic problem concerned the evaluation of the resistance of the studied alloy to cyclic oxidation in an air atmosphere, with particular attention to the influence of temperature, surface roughness and cooling rate from heating temperature to room temperature. The issue analysed was the effect of niobium addition on the corrosion kinetics as a high-melting element causing improved oxidation resistance, contributing to the reduction in the oxidation rate.

The Oxidation Behaviour and Notch Wear Formation of TiAlN Coated Tools Using Different Oxidation Techniques.

This paper proposes a novel approach to assessing oxidation behavior of TiAlN coatings with defined stoichiometry on the rake and flank surfaces. This is based on the multi-parametric comparison of the oxidation effects detected on the coatings' surfaces resulting from static diffusion couple tests. In this experimental study the diffusion couples consisting of Ti-based and Ni-based alloys and coated TiAlN cutting inserts are tested, respectively. The optimum oxidation temperature was determined by annealing the selected TiAlN coating in a high temperature chamber at temperatures: 700 °C, 800 °C, 900 °C and 1000 °C in air. Concurrently, the mass change and corresponding thickness of the Al2O3 oxidized layer were measured and computed. The comparison of oxides produced covers the surface morphologies, chemical elements and phases which were analyzed by means of SEM (scanning electron microscope), EDS (energy dispersive spectroscopy) and XRD (X-ray diffraction techniques). Additionally, scratch tests were performed to assess the penetration depth down to the substrate and coating failure mechanism after oxidation in diffusion couples. An acceptable similarity of Al2O3 films formed on the TiAlN coating surfaces in diffusion couples and machining processes was established.

Incorporation of Corrosion Effects into the Life-Cycle Analysis of AW-2017A-T4 Aluminium Alloy under Bending Moment.

The paper presents the results of fatigue tests of corroded AW-2017A-T4 aluminium alloy samples subjected to an alternating (symmetrical) bending load. Although there are a number of works describing pre-corrosion fatigue in aluminium alloys, relatively few of them concern bending fatigue effects, in some selected alloys only. Here, the AW-2017A-T4 samples were exposed to electrochemical preliminary corrosion by immersion in an electrolyte, a 3.5% solution of NaCl in water. Several variants of series of samples differing in immersion time were tested. Based on the analysis of the results obtained, Basquin's fatigue characteristics were developed and compared to the characteristics of the material in its nominal state, which allowed for conclusions on the influence of corrosion effects. The characteristic curves show the susceptibility of the test material to corrosive processes, which results in a decrease in fatigue life along with the increase of pre-corrosion time. The samples with longer immersion duration revealed larger surface losses and widespread corrosion pits.

Metallographic and Mechanical Research of the O-Ti2AlNb Alloy.

This paper provides the test results of the fatigue crack growth in notched specimens under tension. The tests were performed on plane specimens with external blunt two-sided notches at room temperature. The tested material was O-Ti2AlNb titanium alloy. The tests were carried out at constant load value and constant stress ratio R = 0. The tests were done at the fatigue stand Instron under the loading change frequency of 25 Hz. The results of mechanical and structural tests of the examined alloy were presented. Scanning electron microscopy (SEM) was used in metallography, which allowed for the initial identification of intermetallic phases. The development of fatigue cracks in the tested alloy indicates that there is a tendency for brittle fracturing, which ran along the grain boundary.

Annual Observation of Changes in the Angle of Trunk Rotation. Trunk Asymmetry Predictors. A Study from a Scoliosis Screening in School Adolescents.

Adolescent forms of idiopathic scoliosis are commonly encountered deformities of the thoracic and lumbar spine. They affect a significant number of adolescents, yet their cause is still unknown. The presented research is a cross-sectional analysis of 3933 volunteers (2131 girls and 1802 boys). The participants were primary school students aged 9 to 13 years old. This study determined a relationship between predictors such as: body mass, body height and body mass index (BMI) (independent variables) and angle of trunk rotation (ATR) value (dependent variable). Moreover, a stepwise multiple regression with backward selection was conducted to determine to what extent the dependent variable is explained by body mass, body height and BMI. In the group of 11,12,13-year-old girls, the analyzed results of multiple stepwise regression were statistically significant. Among the all studied predictors, it has been shown that body mass in the 11-year-old girls and body height in 12- and 13-year-old girls are major correlates of a 1-year ATR increase in proximal and main thoracic spine levels.

The Angle of Trunk Rotation in School Children: A Study from an Idiopathic Scoliosis Screening. Prevalence and Optimal Age Screening Value.

(1) Background: Idiopathic scoliosis is a deformity of the growing spine. It affects 2-3% of adolescents; yet its cause is still unknown. At the early stage of idiopathic scoliosis (IS), the signs are not very noticeable. That is why the primarily school-based screening for scoliosis is so important. (2) Methods: This was a cross-sectional analysis of 6850 respondents. Participants were elementary school students in the metropolitan area of Poland. The suspicion of IS was based on detection of three-dimensional deformity of the spine using scoliometer. (3) Results: Respondents were divided into two groups: Angle of trunk rotation (ATR) = 0-3º and ATR > 3º. Presented research using a referral criterion of 5º ATR showed that in the group of participants who had ATR > 3º the largest percentage of 5 degree values was recorded at the second and third measurement level of the spine (30.5%, 31.1%, respectively). Analyzing the differences between the two groups of girls (ATR = 0-3º, ATR > 3º), statistically significant differences were recorded between 9 and 11 years of age (p = 0.0388). Girls with ATR > 3º at all measuring levels are significantly slimmer than girls with ATR 0-3º; (4) Conclusions: Age; sex, and risk of developing angle of trunk rotation are very closely associated. The main thoracic (level 2) and thoraco-lumbar (level 3) level of measuring of the spine appears to be the most differentiating in the diagnosis of scoliosis. Girls with a lower degree of trunk deformity (4-6º trunk rotation), which can present mild scoliosis and those with a higher degree (7º trunk rotation) have lower body mass than girls within the norm.

The impact of polyphenols on Bifidobacterium growth.

Polyphenols are a common group of plant based bioactive compounds, that can affect human health because of their antioxidant and antimicrobial properties as well as free-radical scavenging activity. An increasing interest is observed in the interaction between polyphenols and microbiota occurring in food and the human gut. The aim of the work presented here, was to evaluate the effect of some polyphenolic compounds on the growth of two strains of Bifidobacterium: B. adolescentis and B. bifidum. The influence of some flavonoids: naringinin, hesperidin, rutin, quercetin as well as phenolic acids: gallic, caffeic, p-coumaric, ferulic, chlorogenic, vanillic and sinapic was determined by a 96-well microtiter plate assay. In the experiments the effect of three different concentrations of polyphenols: 2, 20 and 100 µg/ml on the growth of Bifidobacterium strains was investigated. All tested compounds influenced the growth of the examined bacteria. Both stimulatory and inhibitory effects were observed in comparison to the positive control. The strongest impact on the growth of bifidobacteria was observed during the first hours of incubation. The constant inhibitory effect was observed for hesperidin and quercetin addition and was dose-dependent. B. bifidum showed a stronger dependence on phenolic acids content in the medium than B. adolescentis during the first hours of incubation.

Pseudorotaxane based on tetraazamacrocyclic copper complex and dibenzocrown ether.

Host-guest interactions between two electron-rich dibenzocrown ethers and electron deficient macrocyclic copper(II) tetraimine complexes lead to the formation of pseudorotaxane in solution. The interactions are enhanced with the copper(III) complex compared to that of the copper(II) form as shown by the electrochemical studies. The larger--30-membered dibenzocrown donor interacted with the copper complex stronger than the smaller ones as revealed by NMR and electrochemical methods. The thiolated form of the copper(II) tetraimine complex was self-assembled at the gold electrode forming an electroactive monolayer able to interact with the crown ether in the solution. These donor-acceptor interactions lead to an increase of the barrier properties of the layer and decreased the electron transfer rate between the copper centre and the gold electrode surface as proved by the voltammetric data.

Macrocyclic multicenter complexes of nickel and copper of increasing complexity.

Multicenter (bi-, tri-, and tetranuclear) tetraazamacrocyclic complexes were self-assembled from Ni and Cu tetraazamacrocyclic mononuclear units and α,ω-diamines as building blocks. The structures of all compounds studied were proved by spectroscopic methods (ESI MS and NMR spectroscopy). Electrochemical experiments revealed reversible one-electron electrode processes at each of the Ni(2+) and Cu(2+) centers with formation of metal cations in oxidation state +3. Long linkers allow bi- and trinuclear complexes with noninteracting metal centers to be obtained. In the case of the short linkers (e.g. ethylenediamine) higher, trinuclear species are formed as major product. The structures of the bis- and tris-macrocyclic systems were confirmed by single-crystal X-ray diffraction. The tris-macrocyclic systems form cations in the shape of triangles partially filled with counterions and solvent molecules. The cations form positively charged layers, which interact in the crystal lattice with the neighboring negatively charged layers of anions. In solution, the trinuclear complexes exhibit strong host-guest interactions with 9,10-dimethyltriptycene due to complementarity of shape and size of this guest molecule. The association constants were determined by NMR spectroscopy and voltammetry, and very good agreement was obtained. The structural flexibility of the tetranuclear complex with long linkers allows for attractive interactions between the metal-complexing macrocycles that result in folding of the molecule. On the contrary, no folding is possible in the case of short linkers consisting of two CH(2) groups.