Ultrafine grain evolution in a Cu-Cr-Zr alloy during warm multidirectional forging

The microstructure evolution and the deformation behavior of a Cu-0.3%Cr-0.5%Zr alloy subjected to multidirectional forging at a temperature of 673 K under a strain rate of about 10-³ s-¹ were studied. Following a rapid increase in the flow stress during straining to about 1, the strain hardening gradually decreases, leading to a steady-state flow behavior at total strain above 2. The multidirectional forging led to the development of ultrafine grained microstructures with mean grain sizes of 0.9 μm and 0.64 μm in the solution treated and aged samples, respectively. The presence of second phase precipitates promoted the grain refinement. After processing to a total strain of 4, the fractions of ultrafine grains (D < 2 μm) comprised 0.36 and 0.59 in the solution treated and aged samples, respectivel

Induction of dc voltage, proportional to the persistent current, by external ac current on system of inhomogeneous superconducting loops

A dc voltage induced by an external ac current is observed in system of asymmetric mesoscopic superconducting loops. The value and sign of this dc voltage, like the one of the persistent current, depend in a periodical way on a magnetic field with period corresponded to the flux quantum within the loop. The amplitude of the oscillations does not depend on the frequency of the external ac current (in the investigated region 100 Hz - 1 MHz) and depends on its amplitude. The latter dependence is not monotonous. The observed phenomenon of rectification is interpreted as a consequence of a dynamic resistive state induced by superposition of the external current and the persistent current. It is shown that the dc voltage can be added in system of loops connected in series: the dc voltage oscillations with amplitude up to 0.00001 V were observed in single loop, up to 0.00004 V in a system of 3 loops and up to 0.0003 V in a system of 20 loops.Comment: 5 pages, 6 figure

Temperature and strain rate dependence of microstructural evolution and dynamic mechanical behavior in nanocrystalline Ti

The mechanical behavior of commercial purity titanium with a nanocrystalline (NC) grain size was investigated using split Hopkinson pressure bar tests at high strain rates and over a range of temperatures. The study was accompanied by detailed microstructural investigations before and after compression testing. The results show that rotary dynamic recrystallization operates during compressive deformation at strain rates of ~3000 and ~4500 s?1 at temperatures from 298 to 573 K but cells form at 673 K. The dynamic mechanical behavior of NC Ti shows a strong dependence on temperature and strain rate such that the flow stress and the strain hardening rate both increase with increasing strain and decreasing temperature. A constitutive equation is derived to relate the flow stress to the temperature, strain rate and true strain and to predict the yield strength and the peak stress of NC Ti subjected to dynamic deformation at elevated temperatures

Fosfomycin in antibiotic prophylaxis of infectious complications after biopsy of the prostate

Introduction. Biopsy of prostate is a routine urologic procedure. More than 1 million biopsies are performed worldwide annually. The frequency of infectious-inflammatory complications remain high, despite the recommended antibiotic prophylaxis schemes.Aim. The evaluation of  effectiveness and safety of  combined antimicrobial prophylaxis: Fosfomycin and Fluoroquinolones of 3rd generation.Materials and methods. 80 patients underwent prostate biopsy in our study and were divided into 2 groups: the first group of 40 patients received routine prophylaxis: Levofloxacin 500 mg 6 hours before the biopsy and 500 mg per day during 4 days after biopsy. The second group of 40 patients, along with standard prophylaxis as in the first group, additionally after biopsy received Fosfomycin 3 gr single-shot.Results and discussion. In the first group, infectious and inflammatory complications occurred in 8 patients (20%). 12.5% of patients from the first group were hospitalized for paranteral antibiotic therapy. The average length of stay in hospital was 3.4 ± 1.45 days. In all cases, in the first group of patients, E. coli was detected, in 70% of cases fluoroquinolone-resistant strain of the bacterium was received. In the second group of patients now hospitalization was required. One patient out of forty (2.5%) from this group showed signs of urinary tract infection, which was not accompanied by an increase of body temperature, as well as changes in blood and urine tests.Conclusion. Our results show good effectiveness and safety of fosfomicin for antibiotic prophylaxis for transrectal prostate biopsy