Synthesis of graphene foams and their sorption properties of n-hexane

Journal of Porous Materials - The influence of preparation conditions of the graphene foams on their physicochemical properties is shown. Different graphene aerogels were obtained from various...     

Adsorption Properties of Activated Tire Pyrolysis Chars for Phenol and Chlorophenols

The adsorption of phenol (Ph), 4-chlorophenol (4CP), and 2,4-dichlorophenol (DCP) from aqueous solutions on activated tire pyrolysis chars (ATPCs) was studied in a batch system, including both kinetics and equilibrium. Different kinetic models and adsorption isotherms were used to describe the adsorption behavior of the phenols. The kinetic study shows that the process can be described by a pseudo-second-order model. The best fitting results for the equilibrium adsorption data were obtained with the Sips isotherm. Adsorption of the selected phenols on all of the adsorbents increased in the order Ph < 4CP < DCP. The effect of ionic strength and pH on the adsorption was also studied. The results show that the ATPCs could be used as adsorbents for the removal of phenols from aqueous solutions.     

Ethyl-cellulose rumen-protected methionine alleviates inflammation and oxidative stress and improves neutrophil function during the periparturient period and early lactation in Holstein dairy cows

The periparturient period is the most critical phase in the productive cycle of dairy cows and is characterized by impairment of the immune system. Our objective was to evaluate the effect of feeding ethyl-cellulose rumen-protected methionine (RPM) starting at d ?28 from expected parturition through 60 d in milk on biomarkers of inflammation, oxidative stress, and liver function as well as leukocyte function. Sixty multiparous Holstein cows were used in a block design and assigned to either a control or the control plus ethyl-cellulose RPM (Mepron, Evonik Nutrition & Care GmbH). Mepron was supplied from ?28 to 60 d in milk at a rate of 0.09% and 0.10% dry matter during the prepartum and postpartum period. That rate ensured that the ratio of Lys to Met in the metabolizable protein was close to 2.8:1. Blood samples from 15 clinically healthy cows per treatment were collected at d ?30, ?14, 1, 7, 21, 30, and 60 and analyzed for biomarkers of liver function, inflammation, and oxidative stress. Neutrophil and monocyte function in whole blood was measured in vitro at ?14, 1, 7, 21, and 30 d in milk. The statistical model included the random effect of block and fixed effect of treatment, time, and its interaction. Compared with control, ethyl-cellulose RPM increased plasma cholesterol and paraoxonase after parturition. Among the inflammation biomarkers measured, ethyl-cellulose RPM led to greater albumin (negative acute-phase protein) and lower haptoglobin than control cows. Although concentration of IL-1β was not affected by treatments, greater IL-6 concentration was detected in response to ethyl-cellulose RPM. Cows supplemented with ethyl-cellulose RPM had greater plasma concentration of ferric-reducing antioxidant power, β-carotene, tocopherol, and total and reduced glutathione, whereas reactive oxygen metabolites were lower compared with control cows. Compared with control, ethyl-cellulose RPM enhanced neutrophil phagocytosis and oxidative burst. Overall, the results indicate that ethyl-cellulose RPM supply to obtain a Lys-to-Met ratio of 2.8:1 in the metabolizable protein during the periparturient period and early lactation is an effective approach to help mitigate oxidative stress and inflammation as well as enhance liver and neutrophil function in dairy cows.     

Spectroscopic Studies of Nanopowder and Nanoceramics La2Hf2O7:Pr Scintillator

Sintered nanoceramics of Pr‐doped lanthanum hafnate, La₂Hf₂O₇:Pr, were prepared by means of a high‐pressure sintering technique using nanopowders made by Pechini method. Structure, morphology, and spectroscopic properties of the ceramics compared to the starting powder are presented and discussed. Emission and excitation spectra recorded at room temperature as well as at 7 K using synchrotron radiation are presented together with results of luminescence kinetics measurements. In ceramics, at 7 K, the Pr³⁺ luminescence from ³P₀ (blue‐green, green, and red region) and ¹D₂ (red) levels is accompanied by a broad‐band emission located in the 380–530 nm range of wavelengths, whereas powders gives only the Pr³⁺‐related luminescence. Depending on the excitation wavelength, the broad‐band emission maximum moves between 430 and 470 nm indicating superposition of at least two components. In sintered nanoceramics, the lifetimes of Pr³⁺ emissions from ³P₀ and ¹D₂ levels were by 10%–20% shorter compared to the powder. The existence of different luminescence centers was proved by the selective emission decays examination. The fast 5d → 4f luminescence of Pr³⁺ was not observed from either of the two types of La₂Hf₂O₇:Pr materials.     

Modification of the boundary integral equation for the Navier–Lamé equations in 2D elastoplastic problems and its numerical solving

The paper presents the generalization of the modification of classical boundary integral equation and obtaining parametric integral equation system for 2D elastoplastic problems. The modification was made to obtain such equations for which numerical solving does not require application of finite or boundary elements. This was achieved through the use of curves and surfaces for modeling introduced at the stage of analytical modification of the classic boundary integral equation. For approximation of plastic strains the Lagrange polynomials with various number and arrangement of interpolation nodes were used. Reliability of the modification was verified on examples with analytical solutions. Copyright © 2016 John Wiley & Sons, Ltd.     

Model of Mean Flow Stress of Ti‐IF Steel Considering Effect of Phase Transformations

The aim of this work was to describe the deformation resistance of austenitized Ti‐IF steel in the temperature range of 650 to 1100°C by a complex equation. The mean flow stress was determined by an original procedure, based on laboratory rolling of flat samples. Deformation resistance was described by a single formula, using a cumulative function in which particular terms are multiplied by a coefficient of 1 or 0, in dependence on a specific temperature. Calculation of specific coefficients had to be proposed in such a way that they could react to exceeding temperature boundaries between individual phase regions. The developed model can be used for off‐line predictions of power/force parameters in the forming of Ti‐IF steel, in a wide range of conditions of hot and warm deformation.     

Modifying the luminescence characteristics of Lu2O3:Eu large nanocrystals with polycarbonate host

Lu₂O₃:Eu phosphor fine powder with average size of crystallites of about 100–150 nm was synthesized. TEM images proved only an insignificant agglomeration of the phosphor. Using these fine particles and commercial polycarbonate a composite material was prepared in a form of 2 mm thick plate and its spectroscopic properties were compared to the powder. While the emission and luminescence excitation spectra were found very similar in both types of materials, the decay times of the Eu³⁺ red luminescence appeared to drop from 1.8–2 ms for the powder to 0.9–1 ms for the composite, with the latter value being perfectly the same as for the coarse‐grained sintered translucent ceramics. Since the refractive indices of Lu₂O₃ host and the polycarbonate are 1.935 and 1.582, respectively, such a drastic change in the Eu³⁺ emission kinetics could not be fully explained by the variations of this parameter only. This result is with some disagreement with previously published data. POLYM. COMPOS., 37:1330–1334, 2016. © 2014 Society of Plastics Engineers     

Sphingolipid metabolism in colorectal adenomas varies depending on histological architecture of polyps and grade of nuclear dysplasia

Incidence of colorectal cancer (CRC) is growing worldwide. Pathogenetic mechanisms responsible for its onset and progression need further clarification. Colorectal adenomatous polyps are precancerous lesions with malignant potential dependent on histological architecture and grade of nuclear dysplasia. One of the factors conditioning CRC development are abnormalities in sphingolipid metabolism. The aim of this study was to assess the levels of sphingolipids in human colorectal adenomas. The control group (C, n = 12) consisted of patients with no colonic polyps. The examined group consisted of patients with prior diagnosed colonic polyps, qualified to endoscopic polypectomy. This group was further divided due to histological architecture into tubular adenomas group (TA, n = 10), tubulovillous adenomas with low‐grade dysplasia (LGD‐TVA, n = 10), and tubulovillous adenomas group with high‐grade dysplasia (HGD‐TVA, n = 11). In tissue samples, sphingolipd metabolite contents were measured using high performance liquid chromatography (HPLC). In cases of polypoid lesions with low malignancy potential (tubular adenomas), concentration of ceramide, which is characterized by proapoptotic and anti‐proliferative properties, increases compared with control group (p < 0.05), whereas content of sphingosine‐1‐phosphate with anti‐apoptotic and stimulating cellular proliferation properties is reduced in comparison with control group (p < 0.05). On the contrary, in cases of more advanced form of adenomatous polyps (tubulovillous adenomas with high‐grade dysplasia), the ceramide level decreases compared with control group (p < 0.05) while sphingosine‐1‐phosphate concentration is elevated (p < 0.05). We found that concentrations of pro‐apoptotic ceramide are decreased and pro‐proliferative S1P levels are increased in polypoid lesions with high malignancy potential, and it was the opposite in those with low malignancy potential.