Porous nanostructured ZnO films deposited by picosecond laser ablation

Porous nanostructured polycrystalline ZnO films, free of large particulates, were deposited by picosecond laser ablation. Using a Zn target, zinc oxide films were deposited on indium tin oxide (ITO) substrates using a picosecond Nd:YVO₄ laser (8 ps, 50 kHz, 532 nm, 0.17 J/cm²) in an oxygen atmosphere at room temperature (RT). The morpho-structural characteristics of ZnO films deposited at different oxygen pressures (150–900 mTorr) and gas flow rates (0.25 and 10 sccm) were studied. The post-deposition influence of annealing (250–550 °C) in oxygen on the film characteristics was also investigated. At RT, a mixture of Zn and ZnO formed. At substrate temperatures above 350 °C, the films were completely oxidized, containing a ZnO wurtzite phase with crystallite sizes of 12.2–40.1 nm. At pressures of up to 450 mTorr, the porous films consisted of well-distinguished primary nanoparticles with average sizes of 45–58 nm, while at higher pressures, larger clusters (3.1–14.7 μm) were dominant, leading to thicker films; higher flow rates favored clustering.     

Characterization of superconducting wires and cables by X-ray micro-tomography

Due to their mechanical strength and ability to withstand the large electromagnetic force applied to the superconductors in large magnets during excitation, the Cable-in-Conduit-Conductor (CICC) type superconductors will be employed in the next stage of fusion magnets. Here, we discuss the recent results on the application of a non-invasive method for the characterization of CCIC by X-ray micro-tomography (μXCT). The experiments have been carried out on a high resolution X-ray tomograph in INFLPR (http://tomography.inflpr.ro). An open type nanofocus X-ray source with maximum high voltage of 225 kVp at 15–30 W maximum power and multiple targets of W on different windows materials (Be, Al, Cu or diamond) is the main component. X-rays are detected by means of amorphous silicon flat panel sensor in the cone-beam configuration and high-energy efficient line sensor based on individual scintillators in the fan-beam scanning configuration. The quality of tomographic images (≈40 μm space resolution) allowed the majority of strands of analyzed CICC samples to be fully reconstructed along the investigated segment (up to 300 mm long). Our method provides: (i) local and global void fractions (over a 300 mm length of the sample), (ii) void homogeneity factor as the ratio between void space surface and perimeter and (iii) twist pitch angle of individual strands and its distribution in 3D. It can be used to investigate superconducting CICC during their manufacture, installation or after service inspection, for purposes of QA, characterization or development.     

催化重整装置再接触方案探讨

对催化重整装置再接触系统的三种流程：低温再接触,常温再接触和常温再接触＋吸收,从产品收率,公用工程消耗,设备投资和经济效益方面进行了比较,结论是：对于产氢去PSA的重整装置,若PSA的尾气只作为燃料气时,低温再接触流程优于常温再接触流程;若PSA尾气还要去轻烃回收,则再接触可采用常温再接触,不必采用低温再接触。     

Investigations into the mechanisms controlling parturition in cattle

A pronounced increase in fetal cortisol concentrations stimulating an increase in estrogen production at the expense of progesterone precursors in the placenta, luteolysis, and progesterone withdrawal is considered as a key event during the complex signal cascade leading to the initiation of parturition in cattle. However, there are many questions concerning the exact functional and/or temporal relationships between these individual processes which finally result in the expulsion of the calf and the timely release of the placenta. Thus, parturition was induced in 270-day pregnant cows using the progesterone receptor blocker aglepristone (group AG, n=3), the prostaglandin F(2α) analog cloprostenol (group PG, n=4), and the glucocorticoid dexamethasone (group GC, n=4) to characterize the effect on maternal steroid and prostaglandin levels and to identify immediate subsequent changes in placental morphology and gene expression as compared with untreated controls sampled on day 272 (group D272, n=3) and cows during normal parturition (group NT, n=4). All calves of the treatment groups were born on days 271-272, whereas gestational length in NT cows was 280.5±1.3 days. However, none of the treatments significantly induced the prepartal remodeling of placentomes characterized by a decline in trophoblast giant cells and reduction of the caruncular epithelium. Data on placental CYP17 and COX2 expression confirm that these key enzymes are upregulated by GC, whereas placental aromatase expression was not affected by any treatment. Maternal progesterone and prostaglandin profiles suggest differential effects of the treatments on luteal function and placental or uterine prostaglandin production. The results provide new information on the initiation of parturition in cattle but raise many new questions.     

Biofilm formation and the survival of Salmonella Typhimurium on parsley

Although several studies provide evidence that the formation of biofilms by human pathogens on plant tissue is possible, to date there is no direct evidence that biofilms enhance the resistance of plant-associated pathogens to disinfectants or biocides. We hypothesized that biofilm formation would enhance the adhesion and survival of Salmonella on leafy vegetables. To test our hypothesis, we compared the adhesion and persistence of Salmonella Typhimurium and its biofilm-deficient isogenic mutant. Following inoculation of parsley and rinsing with water or chlorine solution, both strains had similar survival properties, and up to 3-log reduction were observed, depending on chlorine concentration. This indicates that the biofilm matrix of Salmonella likely does not play a significant role in initial adhesion and survival after disinfection. After a week of storage the biofilm producing strain survived chlorination significantly better than the biofilm-deficient mutant. However, the recovery of the mutant was still elevated, indicating that although the biofilm matrix has a role in persistence of Salmonella after chlorination treatment of parsley, this is not the most important mechanism, and other mechanisms, probably the ability to penetrate the plant tissue or the pre-existing biofilms, or production of different polysaccharides other than cellulose, provide the protection.     

Inhibitory effects of Lemon balm (Melissa officinalis, L.) extract on the formation of advanced glycation end products

Lemon balm (Melissa officinalis) is a medicinal herb possessing functional compounds with unexplored anti-glycative action. The anti-glycative activity of Lemon balm extract was evaluated in the bovine serum albumin (BSA)/glucose system. The level of glycation, conformational alterations and protein binding to RAGE receptors were assessed by specific fluorescence, Congo red binding assay, circular dichroism, ligand and Western blotting. Ethanol fractions of Melissa leaf exhibited the highest inhibitory effects on the formation of advanced glycation end products (AGEs) and the late stage of glycation process. Significant alteration in the secondary structure of albumin was observed upon glycation, which was mitigated by applying the herb extract. Moreover, upon treatment with balm extract, glycated albumin adopts a secondary structure impeding its detection by RAGE receptors of microglial cells. Our results represent the anti-glycative properties of Melissa extract and its application for possible treatment of AGE-associated diseases.     

Experimental Confirmation of Design Techniques for Effective Bow-Tie Antenna Lengths at THz Frequencies

We present on the relationship between the bow-tie antenna length and its THz spectral emission response. Three well-known approaches for predicting accurate antenna length for a given central frequency were utilized and their validity was experimentally tested. It is shown that the simple quasi-static approach compare to other approximations is valid for frequencies up to ~1.5 THz. The bow-tie THz photoconcudtive (PC) emitter designed using this approximation exhibits THz radiation having the most accurate central frequency compared to the design frequency. Interestingly, the THz PC emitter utilized from this design technique also possesses the optimum radiation bandwidth.