Reconstruction analysis of honeybee colony collapse disorder modeling

Optimization and Engineering - The honeybee has a significant impact on industry and nature. In recent years, a mysterious disease make honeybees die, often losses reach 80–100% of the...     

Characteristics of testing conditions for constitutive models in metal plasticity

We propose a method of identifying constitutive models and material parameters in engineering applications. The presented method is used in the setting of optimal experimental design and is based on successive optimization of a finite set of possible material models. The goal is, for an initially unknown material, to define an optimal test bed based on a given set of constitutive models and a range of possible parameters. As a result of the algorithm, suitable observation operators and external loads are identified. These are then the optimal experimental conditions under which the parameters of the unknown material are tested.     

Pulsed laser deposition of Mn-Zn ferrite thin films

Mn-Zn ferrite thin films were deposited on sapphire substrates by pulsed laser deposition from sintered Mn_{1 – x}Zn _x Fe₂O₄ ceramic targets. A full stoichiometric transfer from targets to substrates was achieved. Magnetic inplane measurements in two perpendicular directions were carried out and the macromagnetic properties of films were determined. The hysteresis loops obtained are rectangular and the values of the coercive force, the saturation, and the remanent magnetization are comparable to the same parameters of the bulk Mn-Zn ferrite. The films were characterized using a vibrating sample magnetometer (VSM), a scanning electron microscope (SEM) and by X-ray photoelectron spectroscopy (XPS).     

A Time-to-Code Converter with a Selection of Time Intervals by Duration

A time-to-code converter with preliminary selection of measured time intervals by duration is described. The intervals are selected with the use of Analog Devices programmable delay generators. The selection time of the measured time intervals is 50 ns, the conversion range is from 0 to 100 ns, and the resolution is 0.1 ns.     

Anaerobic surgical infection

The study covers 125 patients with anaerobic surgical infection, aged 7 to 82 years. Of the total 27 cases are operated for acute cholecystitis, four--diffuse acute peritonitis, seventeen--acute appendicitis, and three--acute hematogenous osteomyelitis. In acute cholecystitis and acute appendicitis microbiological study is carried out of the content, organic wall and periorganic space. In acute cholecystitis patients anaerobic flora is found in 39.01 per cent, and gram-negative--in 44.9 per cent, and in those presenting acute appendicitis--in 28.3 per cent and 58 per cent, respectively. The clinical analysis results point to a severer clinical course in the patients presenting anaerobic flora. The letter becomes manifest as mono infection in 37.2 per cent. It is pointed out that in the presence of two or more signs, characteristic of anaerobic infection, namely: destructive early process, offensive odor and intoxication, anaerobic bacterial flora should be invariably considered. At each microbiological examination the results of staining according to Gram should be also demanded from the laboratory.     

Ion-exchange copolymers based on tetrafluoroethylene,hexafluoropropylene, and acrylic acid

Peroxide-induced copolymerization of tetrafluoroethylene (TFE) with hexafluoropropylene (HFP) and acrylic acid (AA) at different molar ratios of monomers, reaction time, pressure, and initiator concentration was studied. By means of IR spectroscopy and temperature and phase characteristics of the copolymers obtained it was proved that a ternary copolymer of TFE, HFP, and AA was synthesized. Fluoro-containing polymers with ion-exchange capacities up to 0.8 meq/g were obtained. The composition of binary TFE-HFP and ternary TFE-HFP-AA copolymers and some of their characteristics were determined. Copolymerization takes place mainly in the stationary state with an induction period. Polymerization rate R ～ [In]^0.7, which is presumably connected with chain transfer reaction to AA.     

Performance of glucose biosensor based on oxygen electrode in physiological fluids and at body temperature

A potentially implantable glucose biosensor for continuous monitoring of glucose levels in diabetic patients has been developed. The glucose biosensor is based on an amperometric oxygen electrode and glucose oxidase immobilized on carbon powder held in the form of a liquid suspension. The enzyme material can be replaced (the sensor recharged) without sensor disassembly. Diffusion membranes made of silastic coatings over a microporous polycarbonate membrane are used. Calibration curves of the sensors in phosphate buffer solution and in undiluted blood plasma at body temperature have been obtained. The reproducibility of the sensor response in serum at body temperature is demonstrated. The sensors have a stable signal during storage and continuous operation at body temperature for a period of at least one month.     

Modification of the properties of HTSC YBCO thin films on silicon by superfast laser annealing in oxygen with a CW CO2 Laser

The use of superfast CW CO₂ laser annealing in O₂ for modifying the properties of laser deposited Y₁Ba₂Cu₃O_{7 –x} thin films is described. The film resistivity could be controlled reversibly by laser irradiation at 40 W cm^–2. The resistivity was measuredin situ during the annealing process.     

X-ray structure at 1.76 A resolution of a polypeptide phospholipase A2 inhibitor

The high resolution crystal structure of a natural PLA2 inhibitor has been determined by Patterson search methods. In the heterodimeric, neurotoxic complex, vipoxin, isolated from the venom of Bulgarian viper, PLA2 inhibitor represents the non-toxic subunit. The model was refined to a crystallographic R-factor of 15.5% for data between 6 and 1.76 A resolution. The packing of the inhibitor in the crystal reveals close contacts between the molecules, which are symmetry-related by the 2-fold axes of the lattice. These pairs associate as a crystallographic dimer, stabilized by a set of interactions, including van der Waals contacts between residues from symmetry-related pairs, denoted as the recognition site and the recognition surface. Residues Ph3, Trp31 and Tyr119 represent the recognition site of inhibitor which possibly fits to the hydrophobic wall of the target PLA2. The topology of the inhibitor represents the PLA2 type of folding: three long helices and a beta-hairpin. Superposition of the structure of the inhibitor shows an almost complete overlap with different mammalian and viper PLA2 in the backbone and in the position of the sidechains of the residues that belong to the active centre and the hydrophobic wall. A "lock and key" mechanism of recognition of its native PLA2 in gland cells and other toxic PLA2 in vitro has been suggested. The mechanism includes complementary "head to tail" interactions between the recognition site of the inhibitor and a recognition surface located on the hydrophobic wall of the target PLA2. Having a high spatial homology with the PLA2 family of enzymes but opposing their action, the inhibitor from vipoxin presents an example of a divergent evolution of an ancient PLA2. The presence of a space for binding calcium in the inhibitor is believed to be a rudiment and proof of a common origin with PLA2.