Mechanical behavior of bulk nanocrystalline copper alloys produced by high energy ball milling

Copper alloys with different amounts of zinc were synthesized via high energy ball milling at liquid nitrogen and room temperature. Bulk samples were produced in situ by controlling the milling temperature. It is shown that temperature plays an important role in formation of artifact-free consolidated samples via its effect on defect formation and annihilation during the milling process. The mechanical behavior of Cu–Zn nanocrystalline alloys was examined using Vickers microhardness and tensile tests. The nanostructure of the alloys was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hardness results of processed alloys vary as a function of the alloying elements. Considering typical low ductility of nanocrystalline materials, the improved ductility with the high strength observed in these alloys suggests that they are artifact-free and may have several deformation mechanisms, which may include dislocation activity and nano-twinning.     

XV454, a novel nonpeptide small-molecule platelet GIIb/IIIa antagonist with comparable platelet alpha(IIb)beta3-binding kinetics to c7E3

XV454 demonstrated high potency (IC50 = 14-25 nM) in inhibiting human platelet aggregation induced by adenosine diphosphate (ADP, 10 microM), thrombin receptor agonist peptide (TRAP) (10 microM), or collagen (20 microg/ml). XV454 exhibited a high degree of selectivity for platelet alpha(IIb)beta3 in comparison with c7E3, which is a nonspecific antagonist for both alpha(IIb)beta3 and alpha(v)beta3. Both XV454 and c7E3 bind with high affinity to either activated (A) or unactivated (U) human, baboon, or canine platelets. XV454 binds with a relatively higher affinity [Kd = 0.5 nM (A), 0.6 nM (U)] as compared with c7E3 [Kd = 9.1 nM (A), 9.2 (U) nM]. XV454 demonstrated a tight association with human, baboon, and, to a lesser extent, with canine platelets (t(1/2) of dissociation = 110 +/- 6, 80 +/- 10, and 23 +/- 2 min, respectively). Both c7E3 and XV454 associate tightly with a slower dissociation rate with unactivated human platelets: t(1/2) of 42 and 116 min, respectively. In non-human primates, oral (0.1 mg/kg, p.o.) and intravenous (0.05 mg/kg, i.v. bolus administration of XV454 methyl ester pro-drug resulted a long-lasting maximal antiplatelet efficacy for < or = 72 h with significant but reversible prolongation of bleeding time and without effects on platelet count, clinical chemistry, or hemodynamic profile. In conclusion, XV454 represents a potent antiplatelet agent in inhibiting platelet aggregation along with a high affinity and relatively slow dissociation rate from human platelet GPIIb/IIIa receptors that allow a long-lasting antiplatelet efficacy after single i.v. or oral administration.     

Variable structure control of a robotic arm in the presence of uncertainty

Based on the theory of variable structure systems (VSS), control system design for the trajectory control of robotic systems is presented. It is assumed that the parameters of the system are uncertain and unknown frictional torques are acting at the various joints of the arm. For simplicity, the control of a three-link PUMA arm is considered. For trajectory following, two control laws, C_H and C_θ, based on the choice of coordinates of the end effector or joint angles as the controlled outputs, respectively, are derived. It is seen that whereas control C_θ has no singularity, certain singular surfaces arise where feedback elements of C_H become infinity. These singular surfaces describe the boundary of the reachable region (workspace). Digital simulation results are presented to show that accurate trajectory following can be accomplished using the control C_H or C_θ for large maneuvers of the arm in spite of the uncertainty in the system.     

Analysis and design consideration of mean temperature differential Stirling engine for solar application

This article presents a technical innovation, study of solar power system based on the Stirling dish (SD) technology and design considerations to be taken in designing of a mean temperature differential Stirling engine for solar application. The target power source will be solar dish/Stirling with average concentration ratio, which will supply a constant source temperature of 320 °C. Hence, the system design is based on a temperature difference of 300 °C, assuming that the sink is kept at 20 °C. During the preliminary design stage, the critical parameters of the engine design are determined according to the dynamic model with losses energy and pressure drop in heat exchangers was used during the design optimisation stage in order to establish a complete analytical model for the engine. The heat exchangers are designed to be of high effectiveness and low pressure-drop. Upon optimisation, for given value of difference temperature, operating frequency and dead volume there is a definite optimal value of swept volume at which the power is a maximum. The optimal swept volume of 75 cm³ for operating frequency 75 Hz with the power is 250 W and the dead volume is of 370 cm³.     

Municipal solid waste compost application improves productivity, polyphenol content, and antioxidant capacity of Mesembryanthemum edule

Organic wastes were successfully used as soil amendment to improve agrosystems productivity. Yet, the effectiveness of this practice to enhance plant antioxidant capacities has received little attention. Here, we assess the effect of municipal solid waste (MSW) compost (at 40 t ha(-1)) on growth, polyphenol contents and antioxidant activities of Mesembryanthemum edule. MSW compost application significantly increased the soil contents of carbon, nitrogen, calcium, phosphorus and potassium. This was associated with higher nutrient (N, P, and K) uptake, which likely led to the significant improvement of the plant biomass and relative growth rate (RGR) (+93% on average) as compared to the control. In the same way, the fertilizing effect of the added organic matter significantly enhanced the antioxidant potential M. edule, assessed by radical scavenging activity, iron reducing power and β-carotene bleaching capacity. This was associated with significantly higher antioxidant contents, mainly total phenols and flavonoids. Heavy metal (Pb, Cd, Cu, and Zn) concentrations were slightly increased upon compost application, but remained lower than phytotoxic values. Overall, our results point out that short-term MSW compost application at 40 t ha(-1) is efficient in enhancing the productivity together with the antioxidant potentiality of M. edule without any adverse environmental impact.     

An effective DeepWINet CNN model for off-line text-independent writer identification

Pattern Analysis and Applications - Writer identification based on handwriting recognition is considered one of the most common research areas in pattern recognition and biometrics. It has...     

Electrogenerated base-promoted synthesis and antimicrobial activity of 2-imino-1,3-thiazolidin-4-one derivatives

Electrogenerated cyanomethylanions obtained by reduction of dry acetonitrile at a steel grid cathode were used to promote the addition of ethyl bromoacetate to thiourea derivatives. The reaction yields the corresponding 2-imino-1,3-thiazolidin-4-one. The reaction pathway was discussed based on the kinetic and thermodynamic data obtained by computational methods. In addition, the biological activity of these new compounds was also investigated.     

Microscopic measurement of cellular infiltration in the rheumatoid arthritis synovial membrane: a comparison of semiquantitative and quantitative analysis

BACKGROUND: A significant proportion of burn patients with inhalation injuries incur difficulties with airway protection, dysphagia, and aspiration. In assessing the need for intubation in burn patients, the efficacy of fiberoptic laryngoscopy was compared with clinical findings and the findings of diagnostic tests, such as arterial blood gas analysis, measurement of carboxyhemoglobin levels, pulmonary function tests, and radiography of the lateral aspect of the neck. OBJECTIVE: To determine if these patients were at risk for aspiration or dysphagia, barium-enhanced fluoroscopic swallowing studies were performed. DESIGN: Prospective study. SETTINGS: Burn intensive care unit in an academic tertiary referral center. MAIN OUTCOME MEASURES: Need for endotracheal intubation and potential for aspiration. RESULTS: Six (55%) of 11 patients had clinical findings and symptoms that indicated, under traditional criteria, endotracheal intubation for airway protection. Visualization of the upper airway with fiberoptic laryngoscopy obviated the need for endotracheal intubation in all 11 patients. These patients also failed to evidence an increased risk of aspiration or other swallowing dysfunction. CONCLUSIONS: In comparison with other diagnostic criteria, fiberoptic laryngoscopy allows differentiation of those patients with inhalation injuries who, while at risk for upper airway obstruction, do not require intubation. These patients may be safely observed in a monitored setting with serial fiberoptic examinations, thus avoiding the possible complications associated with intubation of an airway with a compromised mucosalized surface. In these patients, swallowing abnormalities do not manifest.     

A wavelet-based technique for discrimination between faults and magnetizing inrush currents in transformers

This paper presents the development of a wavelet-based scheme, for distinguishing between transformer inrush currents and power system fault currents, which proved to provide a reliable, fast, and computationally efficient tool. The operating time of the scheme is less than half the power frequency cycle (based on a 5-kHz sampling rate). In this work, a wavelet transform concept is presented. Feature extraction and method of discrimination between transformer inrush and fault currents is derived. A 132/11-kV transformer connected to a 132-kV power system were simulated using the EMTP. The generated data were used by the MATLAB to test the performance of the technique as to its speed of response, computational burden and reliability. The proposed scheme proved to be reliable, accurate, and fast.