Unit fracture energy of certain metals and alloys in thermal shock

An energy-based approach is used to examine the problem of cleavage fracture. The approach is based on a comparison of the store of energy in the specimen and the work done in its fracture. A series of approximate calculations is performed with the use of the program UP-OK to determine the critical unit fracture energy _* necessary to complete the fracture work and fragment the specimen over a period within the submicrosecond range. The specimens were made of titanium (VT1-0), brass (L62, L63), bronze (BrB2, BrB2M), and molybdenum (MCh-1) and had a thickness within the range 0.01–1 mm. They were subjected to a brief pulse of x radiation from a nuclear explosion. The estimates that were obtained showed that the critical unit fracture energy _* is not a material constant but instead depends on the loading conditions. It increases with an increase in the time of action of the tensile stresses in the cleaved cross section.Translated from Problemy Prochnosti, No. 6, pp. 27–32, November–December, 1996.     

On the use of silicone liquids in power transformers

The insulation and basic physical characteristics of insulation liquids MIDEL 7131 (ester) and SOFEKSIL–TSZh (silicone liquid) are considered. It is shown that the SOFEKSIL–TSZh liquid is characterized by a higher flash point, which is important for providing the fire safety of high-voltage electrical equipment. Taking into account that contradictory data on the electrical strength of silicone liquids are contradictory, studies on the electric strength of the SOFEKSIL–TSZh liquid and transformer oil have been performed for sharply nonuniform fields at an impulse voltage of 1.2/50 μs for both polarities. It is shown that the electric strength of the SOFEKSIL–TSZh liquid is similar to the electric strength of GK transformer oil and MIDEL 7131 liquid. It is concluded that the SOFEKSIL–TSZh liquid can be used in power transformers in the case of increased requirements for fire safety.     

Five year water and nitrogen balance for a constructed surface flow wetland treating agricultural drainage waters

The performance of a constructed surface flow wetland in reducing diffuse N pollution coming from croplands is being investigated in an ongoing experiment, begun in 1998 in NE Italy. The 0.32 ha wetland is vegetated with Phragmites australis (Cav.) Trin. and Typha latifolia (L.). It receives drainage water from 6 ha of land managed for an experiment on drainage systems, where maize, sugarbeet, winter wheat and soybean are cultivated. During the period 1998-2002, the wetland received from 4698 to 8412 mm of water per year (on average, about 9 times the environmental rainfall); its water regimen was discontinuous and flooding occurred on a variable number of days per year (from 13 to 126). Nitric nitrogen was the most important form of element load. Its concentration in the inflow water over time was rather discontinuous, with median values ranging from 0.2 (in 2001) to 4.5 (in 2000) mg L(-1). Inflow nitric N concentrations were occasionally in the 5-15 mg L(-1) range. Concentrations reduced passing through the wetland, with a more evident effect in the last year. Over 5 years, the wetland received slightly more than 2000 kg ha(-1) of nitrogen, 87% in nitric form mostly from farmland drainage. The remaining 13% of N was applied as organic slurry directly onto the wetland, with 5 distributions during 1998 to assess wetland performance in treating occasional organic loads. Field drainage loads had a discontinuous time pattern and occurred mostly during autumn-winter, with the exception of the 2001-2002 season which was a very dry. The wetland discharged 206 kg ha(-1) of N, over the 5-year period, with an apparent removal efficiency of about 90%. The disappearance was mostly due to plant uptake (1110 kg ha(-1)) and soil accumulation (570 kg ha(-1)), with the contribution of denitrification being estimated at around 7%.     

Influence of blood transfusions on surgery-induced immune changes in colorectal carcinoma

Perioperative blood transfusions have been shown to enhance recurrence rates in patients with operable solid tumors, perhaps by inducing immunosuppression through unknown mechanisms. Since the surgical treatment per se has been proven to induce immune alterations, the present study was carried out to evaluate the immune effect of blood transfusions on surgery-induced immune variations. The study included 27 patients with resectable colorectal carcinoma, 18 of whom received no transfusion, while the other 9 received blood transfusions in the perioperative period. Total lymphocytes, total T lymphocytes (CD3) and soluble IL-2 receptor serum levels (SIL-2R) were measured on venous blood samples collected from each patient either before or 7 days after surgery. Both in non transfused and in transfused patients, SIL-2R mean levels were significantly higher after than before surgery. Their increase was associated with a significant decrease in both lymphocytes and CD3 cells in non-transfused patients, while in the transfused ones lymphocytes and CD3 cells did not show significant changes with surgery. This study shows that blood transfusions modify the relation between changes in SIL-2R and those in lymphocyte number induced by major surgery. It remains to be understood which relation exist between these immune effects and the promoting action of blood transfusion on relapse frequency in cancer.     

Molecular characterization of antimicrobial resistance in Klebsiella pneumoniae isolated from Brazilian dairy herds

In this observational study, phenotypic and genotypic patterns of antimicrobial resistance (AMR) in Klebsiella pneumoniae isolated from intramammary infections, clinical mastitis, fresh feces, rectal swabs, animal hindlimbs, and bulk tank milk samples from Brazilian dairy herds were investigated. In addition, we identified specific genetic variants present among extended-spectrum β-lactamase (ESBL) producers. We obtained 169 isolates of K. pneumoniae from 2009 to 2011 on 24 Brazilian dairy farms located in 4 Brazilian states. The AMR profile of all isolates was determined using disk-diffusion assays. The antimicrobial panel included drugs commonly used as mastitis treatment in Brazilian dairy herds (gentamicin, cephalosporins, sulfamethoxazole-trimethoprim, tetracycline) as well as antimicrobials of critical importance for human health (meropenem, ceftazidime, fluoroquinolones). The K. pneumoniae isolates resistant to tetracycline, fluoroquinolones, sulfamethoxazole-trimethoprim, or chloramphenicol were screened for presence of drug-specific AMR genes [tet, qnr, aac(6')-Ib, floR, catA2, cm1A, dfr, sul] using PCR. In addition, we identified ESBL genes present among ESBL-producers by using whole genome sequencing. Genomes were assembled and annotated, and patterns of AMR genes were investigated. Resistance was commonly detected against tetracycline (22.5% of all isolates), streptomycin (20.7%), and sulfamethoxazole-trimethoprim (9.5%). Antimicrobial resistance rates were higher in K. pneumoniae isolated from intramammary infections in comparison with isolates from feces (19.2 and 0% of multidrug resistance in intramammary and fecal isolates, respectively). In contrast, no difference in AMR rates was observed when contrasting hind limbs and isolates from intramammary infections. The genes tetA, sul2, and floR were the most frequently observed AMR genes in K. pneumoniae resistant to tetracycline, sulfamethoxazole-trimethoprim, and chloramphenicol, respectively. The tetA gene was present exclusively in isolates from milk. The genes bla_CTX-M8 and bla_SHV-108 were present in 3 ESBL-producing K. pneumoniae, including an isolate from bulk tank milk. The 3 isolates were of sequence type 281 and had similar mobile genetic elements and virulence genes. Our study reinforced the epidemiological importance and dissemination of bla_CTX-M-8 pST114 plasmid in food-producing animals in Brazil.     

Production of lipid microparticles containing bioactive molecules functionalized with PEG

The functionalization of bioactive principles is a relevant issue as it allows increasing their stability, to raise the hydrophilic properties of hydrophobic materials, to reduce the absorption from macrophages and the proteolytic degradation. For this reason, we have functionalized a model protein (Ribonuclease A) with polyethylene glycol (PEG₅₀₀₀).We have investigated the production of lipid/PEG particles incorporating this active principle by a supercritical fluid technology (particles from gas saturated solution, PGSS) to obtain solid micro- and nanoparticles.Runs were carried out to study the process conditions; thus, the effects of the operative variables, such as temperature, pressure and organic solvent, were optimized to obtain micrometric particles.The particles produced were characterized by static light scattering (SLS) to determine their mean and distribution size. The better operative conditions were employed to produce microparticles incorporating Ribonuclease A (RNAse) as both native and PEGylated form.The BCA test was applied to determine the maximum amount of protein incorporated in the particles and the in vitro release. The retained enzymatic activity of proteins after the PEGylation and after the micronization process was also determined by spectrophotometric evaluation.     

Retrospective evaluation of lead contamination in honey from 2005 to present in northeastern Italy and future perspectives in the light of updated legislation

Lead is a naturally occurring element but largely originating from human activities. Food is the major source of exposure to lead for humans and the publication of a scientific opinion from the European Food Safety Authority on the risks to human health related to the presence of lead in foodstuffs, led European Union to establish more restrictive limits for this contaminant in food from 1 January 2016. In particular, a maximum level of 0.10 mg kg^?1 was established for honey. The retrospective evaluation of 995 honey samples analysed since 2005, revealed a progressive reduction in the concentration of lead, with a mean value of 0.045 mg kg^?1 in 2015. Total 1.5% of honeys analysed in 2015 exceeded the maximum lead level and therefore will no longer be marketable. Interested beekeepers should clarify the causes of honey contamination and adopt corrective actions to keep their honey production within the legal levels of lead.