Plane Problem for Layered Composites with Periodic Array of Interfacial Cracks Under Compressive Static Loading

The current paper addresses the problem of 2-D modelling of the onset of failure process in a layered composite with periodic array of interfacial cracks under static compression along layers. The statement of the problem is based on the most accurate approach, the model of piecewise-homogenous medium. The condition of plane strain state is considered. The shear and the extensional buckling modes are examined. The laminae are modelled by transversally isotropic material (a matrix reinforced by continuous parallel fibres). The complex non-classical failure mechanics problem is solved utilizing finite element analysis. It is found that the 0°-plies volume fraction, the crack length and the mutual position of cracks influence the critical strain in the composite.     

Microstructure and Mechanical Properties of the Ductile Al–Ti–Mo–Nb–V Refractory High Entropy Alloys

Metallurgical and Materials Transactions A - A number of non-equimolar refractory high entropy alloys (RF HEAs) from the Al–Ti–Mo–Nb–V system are synthesized, with the...     

Influence of surface modification of alumina on bond strength in Al2O3/Al/Al2O3 joints

The subject of the work was to study the effect of Ti thin film on alumina ceramic on mechanical strength and fracture character of Al₂O₃/Al/Al₂O₃ joints. The joints were formed by liquid state bonding of alumina substrates covered with titanium thin film of 800 nm thickness using Al interlayer of 30μm thickness at temperature of 973 K in a vacuum of 0.2 mPa for 5 min. The bend strength was measured by four–point bending test at room temperature. Scanning and transmission electron microscopy were applied for detailed characterization of interface structure and failure character of fractured joint surfaces. Result analysis has shown that application of the Ti thin film on alumina leads to decrease of bond strength properties of Al₂O₃/Al/Al₂O₃ joints along with the change either of structure and chemistry of interface or of failure character.     

Synthesis of Novel Phosphonic‐Type Activity‐Based Probes for Neutrophil Serine Proteases and Their Application in Spleen Lysates of Different Organisms

Neutrophils are a type of granulocyte important in the “first line of defense” of the innate immune system. Upon activation, they facilitate the destruction of invading microorganisms by the production of superoxide radicals, as well as the release of the enzymatic contents of their lysozymes. These enzymes include specific serine proteases: cathepsin G, neutrophil elastase, proteinase 3, as well as the recently discovered neutrophil serine protease 4 (NSP4). Under normal conditions, the proteolytic activity of neutrophil proteases is tightly regulated by endogenous serpins; however, this mechanism can be subverted during tissue stress, thereby resulting in the uncontrolled activity of serine proteases, which induce chronic inflammation and subsequent pathology. Herein, we describe the development of low‐molecular‐weight activity‐based probes that specifically target the active sites of neutrophil proteases.     

Relationship of ergosterol content and fungal contamination and assessment of technological quality of malting barley preserved in a metal silo using the near-ambient method

Environmental microbiologists frequently use ergosterol, a fungal-specific membrane lipid, as an indicator of fungal infection in grain and other plant materials. Microbiological loading and technological quality of barley was determined directly after harvest, after post-harvest drying, and during storage. The conventional plate count method was used to measure fungal contamination (CFU). Ergosterol concentration (ERG) was determined by extraction, saponification and quantification using high-performance liquid chromatography (HPLC) with UV detection. The laboratory malting method was used to determine technological quality of the malt. Results showed a significant correlation between ERG and CFU (the coefficient of correlation was 0.92). Analyses also indicated that the high germinative energy and technological quality of the malt produced from dried barley was retained.     

Treatment of adrenoleukodystrophy with bone marrow transplantation

Three children with adrenoleukodystrophy (ALD) underwent allogeneic bone marrow transplantation (BMT) between 1992 and 1993. The first boy had attention deficits, marked neuropsychological deficits and widespread demyelination in the frontal lobes on MRI before transplantation. Four years later he has mentally deteriorated and the demyelination on MRI has progressed. The second boy had no symptoms but had white matter lesions on MRI when diagnosed. He was regularly followed with MRI and neuropsychological investigations until BMT 18 months later. A progress of the lesions was noted on the initial MRI investigations, and 4 months before BMT a worsening of deficits in attention and kinaesthetic praxis could be observed. He rapidly deteriorated after the transplantation and died 18 months later. Both PCR and in situ hybridization confirmed the presence of donor cells in the brain. The third boy had no symptoms but white matter lesions on MRI when diagnosed. The neuropsychological tests remained normal but a slight progress was observed on MRI just before transplantation. This boy is still healthy 3.5 years after BMT. BMT as treatment for ALD has to be considered very early, even if a child without symptoms but signs of demyelination on MRI, if a suitable donor is available.     

Risk factors for chronic graft-versus-host disease after bone marrow transplantation: a retrospective single centre analysis

We retrospectively compared the changes in serum albumin concentration and colloid osmotic pressure between survivors and nonsurvivors of prolonged (> or = 7 days) critical illness over a 2-year period from 1 July 1995. All patients had serum albumin measured daily, and colloid osmotic pressure measured 5 days a week, throughout their ICU admission. They received crystalloid and colloid infusions as well as parenteral or enteral feeding. Infusions of albumin were not used to treat hypoalbuminaemia. One hundred and forty-five patients were included, 66 nonsurvivors and 79 survivors. Nonsurvivors were significantly older than survivors [mean (95% CI): 58 (3.8) and 49 (4.1) years, respectively] and had a greater risk of death [mean (95% CI): 0.44 (0.06) and 0.28 (0.05); p < 0.05]. There was no significant difference in gender, APACHE II score [mean (95% CI): 22 (2.7) (nonsurvivors); 18 (2.3) (survivors)] or length of stay [median (interquartile range): 14 (9-27) days (nonsurvivors); 15 (9-26) days (survivors)]. There was no difference between the two groups in the absolute minimum serum albumin concentrations reached, the time to reach that minimum or the minimum in the first 7 days. However, nonsurvivors had a significantly lower mean serum albumin concentration: [mean (95% CI): 15.7 (5.1) g.l-1 compared with 18.3 (4.6) g.l-1 in survivors; p < 0.05]. They also had a lower recovery mean (the weighted mean after the minimum value): [mean (95% CI): 13.3 (5.1) g.l-1 (nonsurvivors) and 18.6 (5.3) g.l-1 (survivors); p < 0.01]. Analysis of colloid osmotic pressure results showed no difference between the groups in mean, minimum or recovery mean. Regression analysis of mean colloid osmotic pressure and albumin revealed that albumin only contributed 17% of the colloid osmotic pressure in these patients. The similar decrease in albumin in nonsurvivors and survivors may reflect the acute inflammatory response and/or haemodilution. However, survivors showed an ability to increase serum albumin concentrations, possibly owing to resumption of synthesis. The colloid osmotic pressure varied little between or within either group of patients, possibly because of the use of artificial colloids. There was no relationship between death and colloid osmotic pressure.     

Development study of a small,specialized CAD system

SNOB is a small CAD system, developed for the statical analysis and partial design of buildings of cross-wall construction. It is particularly suited for the design of large precast panel blocks of flats. This paper is a case study of its development, during which great attention was paid to controlled growth, user comfort, effectiveness and economy.     

Investigation of structural order and morphology of MCM-41 mesoporous silica using an experimental design methodology

A 2⁴ factorial experiment program was carried out to study the main and interaction effects of four factors (mixture CTMABr/SiO₂, H₂O/SiO₂, and EthAc/SiO₂, and reaction time) on pore ordering, hexagonal unit cell parameter a₀, and morphology of MCM-41. The MCM-41 was synthesized from a sodium silicate solution using cetyltrimethylammonium bromide (CTMABr) surfactant and ethyl acetate (EthAc) pH modifier. None of the factors acted independently to determine pore ordering, in contrast to earlier limited literature data, which suggested a higher CTMABr/SiO₂ disturbs the assembly of the MCM-41 structure. However, there is no contradiction between these results considering that the poorly ordered product was obtained previously from a reaction mixture with the higher EthAc/SiO₂ and lower H₂O/SiO₂, which are shown to hinder pore ordering. A combination of these factors, resulting in a higher concentration of acetic acid (hydrolysis of EthAc), and thus, in a lower mixture alkalinity, implies that the pH affects pore ordering in MCM-41. This is consistent with extensive literature data on this mesoporous material. A small (up to ∼5%) variation of a₀ due to the reaction composition and time variation was insignificant compared to the reported doubling of a₀ caused by the effects of varying the surfactant alkyl chain length, addition of swelling organic compounds, or hydrothermal restructuring. Particle morphology (hexagonal platelets, gyroids, and crescent-like or worm-shaped particles) depended on the combination of mixture CTMABr/SiO₂, H₂O/SiO₂, and EthAc/SiO₂. This is consistent with the literature evidence that morphogenesis of hexagonally ordered silica is a complex phenomenon involving a variety of reaction variables.