The effect of surface texturing on seizure resistance of a steel-bronze assembly

The tribosystem consisted of a stationary block pressed at a required load P against a ring rotating at a defined speed. Sliding was unidirectional. Block samples, made from bronze CuSn10P with 138-HB hardness, were modified using a burnishing technique to obtain surfaces with circular oil pockets. Rings were made from 42CrMo4 steel, of hardness 40 HRC, which was obtained after heat treatment. Tests were conducted at a constant speed of 0.27 m/s. Before the test, an oil drop was added to lubricate sliding surfaces. A seizure resistance test was carried out at constant normal load of 2700 N. Tribotests were automatically stopped when the coefficient of friction reached a limit value 0.15. Selected textured samples clearly exhibited a lifetime longer than untextured reference specimens.     

Influence of confinement on conformational entropy of a polymer chain and structure of polymer-nanoparticles complexes

Behaviour of a polymer chain in the presence of fixed obstacles has been studied by the static Monte Carlo simulations. A modified self-avoiding walk on a cubic lattice has been used to model the polymer in an athermal solution. The statistical counting method has been applied to calculate the conformational entropy of the chain, assumed to be grafted to an obstacle. Different chain lengths and obstacle curvatures have been examined. Some implications of the confinement induced changes in the conformational entropy of polymer chains to the structure of complexes composed of long polymer chains and nanoparticles are discussed.     

VEGFR-1 Overexpression Identifies a Small Subgroup of Aggressive Prostate Cancers in Patients Treated by Prostatectomy

The VEGFR-1 is suggested to promote tumor progression. In the current study we analyzed prevalence and prognostic impact of the VEGFR-1 by immunohistochemistry on a tissue microarray containing more than 3000 prostate cancer specimens. Results were compared to tumor phenotype, ETS-related gene (ERG) status, and biochemical recurrence. Membranous VEGFR-1 expression was detectable in 32.6% of 2669 interpretable cancers and considered strong in 1.7%, moderate in 6.7% and weak in 24.2% of cases. Strong VEGFR-1 expression was associated with TMPRSS2:ERG fusion status as determined by fluorescence in situ hybridization (FISH) and immunohistochemistry (p < 0.0001 each). Elevated VEGFR-1 expression was linked to high Gleason grade and advanced pT stage in TMPRSS2:ERG negative cancers (p = 0.0008 and p = 0.001), while these associations were absent in TMPRSS2:ERG positive cancers. VEGFR-1 expression was also linked to phosphatase and tensin homolog (PTEN) deletions. A comparison with prostate specific antigen (PSA) recurrence revealed that the 1.7% of prostate cancers with the highest VEGFR-1 levels had a strikingly unfavorable prognosis. This could be seen in all cancers, in the subsets of TMPRSS2:ERG positive or negative, PTEN deleted or undeleted carcinomas (p < 0.0001 each). High level VEGFR-1 expression is infrequent in prostate cancer, but identifies a subgroup of aggressive cancers, which may be candidates for anti-VEGFR-1 targeted therapy.     

A numerical investigation of the refrigerant maldistribution from a header towards parallel channels in an evaporator of automotive air conditioning system

Evaporators in automotive air conditioning are designed as compact heat exchangers with the aim to cool outside air for the widest possible range of weather conditions. Under low operating loads a non-uniformity of the refrigerant liquid and gas phase distribution from the evaporator headers towards the evaporating channels leads to a decrease of the evaporator efficiency and a temperature stratification in the exit stream of cooled air. This malfunction is investigated by numerical simulations and analyses with the Computational Multi-Fluid Dynamic code. The applied numerical approach is validated for available experimental conditions. In order to eliminate the air exit temperature stratification, numerical experiments are performed with design changes of the evaporator header and the effectiveness of applied measures is demonstrated.     

Phenomena that accompany the condensation of R404A refrigerant in multiports during hydrodynamic instabilities

Experimental research results are presented concerning the condensation of the R404A refrigerant in a five-channel multiport, which is fed in parallel and consists of mini-channels with internal diameter d = 0.90 and 3.30 mm. The research was performed in the presence of periodic instabilities generated in a frequency range from 5 to 0.2 Hz. During condensation in the multiport, the impact of instabilities is considerably stronger that in the case of single mini-channels. It was found that the temperature profiles and pressure profiles became deformed in each of the mini-channels of the multiport during the condensation process with the generated instabilities. These deformations decreased the value of heat transfer coefficient h, whose value depends on the diameter d of the multiport mini-channels, vapour quality x and the frequency f of the disturbances generated.     

Effect of surface ligands on the optical properties of aqueous soluble CdTe quantum dots

We investigate systematically the influence of the nature of thiol-type capping ligands on the optical and structural properties of highly luminescent CdTe quantum dots synthesized in aqueous media, comparing mercaptopropionic acid (MPA), thioglycolic acid (TGA), 1-thioglycerol (TGH), and glutathione (GSH). The growth rate, size distribution, and quantum yield strongly depend on the type of surface ligand used. While TGH binds too strongly to the nanocrystal surface inhibiting growth, the use of GSH results in the fastest growth kinetics. TGA and MPA show intermediate growth kinetics, but MPA yields a much lower initial size distribution than TGA. The obtained fluorescence quantum yields range from 38% to 73%. XPS studies unambiguously put into evidence the formation of a CdS shell on the CdTe core due to the thermal decomposition of the capping ligands. This shell is thicker when GSH is used as ligand, as compared with TGA ligands.     

Nanostructured ferrites: Structural analysis and catalytic activity

In this work, we have investigated the structural and catalytic properties of Co, Cu and Ni spinel ferrites. Nanostructured ferrites with particle diameters varying from 3 to 10 nm were obtained by the co-precipitation process. X-ray diffraction, X-ray fluorescence, X-ray photoelectron spectroscopy and Mössbauer spectroscopy were used for chemical and structural characterization. The catalytic efficiency of the samples was evaluated by the decomposition of hydrogen peroxide and by the oxidation of methylene blue, monitored via UV–vis spectrophotometry. We observed that the presence of cobalt ions is a crucial factor required to achieve a systematic efficiency of the catalyst in the H₂O₂ decomposition. In contrast, Cu ferrites presented the better performance in methylene blue oxidation, which can be attributed to the different redox properties of Cu and the easier availability of electrons to participate in the oxidation of organic compounds.     

PHOTOCATALYTIC PURIFICATION OF SOIL CONTAMINATED WITH OIL USING MODIFIED TiO2 POWDERS

Photocatalysts based on titanium dioxide were used for the purification of contaminated soil polluted by oil. Commercially produced slurry of titanium dioxide was modified with barium, potassium and calcium. The experiments were performed under natural conditions in summer months (July and August), applying direct solar light, which occurs in Poland. The preparation of photocatalyst samples and the experimental results obtained from the photocatalytic oil decomposition in the soil are presented. The most active photocatalyst for soil purification was titanium dioxide modified with calcium.     

冲击波测量法检验含铝非理想炸药的能量释放（英）

将有机玻璃紧贴于炸药柱,当爆轰波铅药柱传播至界面时发即在有机玻璃中引起一个强烈的冲击波。利用一特定装置分别测定在ＮＨ４ＮＯ３／ＴＮＴ８０／２０,ＮＨ４ＮＯ３／ＴＮＴ／Ａｌ８０／１０／１０,ＮＨ４ＮＯ３／ＴＮＴ／Ｌｉ８０／１０／１０和ＮＨ４ＮＯ３／Ａｌ９０／１０等炸药爆轰作用下有机玻璃中冲击波的传播速度,以检验含铝非理想炸药的能量释放。结果表明,冲击波速度随着传播距离的增加而降低;铝粉颗粒越细,冲击