Cu-Zn powders as potential Cr(VI) adsorbents for drinking water.

This work examines the possibility of applying CuZn alloys as a reducing medium for the efficient removal of hexavalent chromium from drinking water. In an effort to develop a route for producing powders of CuZn alloys under mild conditions and investigate the optimum composition for such application, a series of alloys in the form of powders were prepared, by a sequence of Cu and Zn ball-milling and low temperature annealing. Batch Cr(VI) removal tests, performed to evaluate and compare the efficiency of the products under typical natural water parameters (pH 7 and natural-like water), indicated that the best performing material have a composition around 50 wt% Cu. The dominant reduction mechanisms are both the corrosion of the alloy surface and the electron transfer to the solution. The behavior of granulated CuZn media was tested in rapid-scale column tests using the commercial KDF which verified the high potential of CuZn alloys in Cr(VI) removal. Nevertheless, Cu and Zn leaching problems should be also considered.

Selective homoepitaxial growth and luminescent properties of ZnO nanopillars.

High spatial density ZnO nanopillars (NPs) have been fabricated on catalyst- and pattern-free Si wafers using atmospheric pressure metal organic chemical vapor deposition (APMOCVD) at a moderate temperature (500 °C). The nanopillar diameter is ∼ 35 nm and the length is ∼ 150 nm, with a density of ∼ 2 × 10(9) cm( - 2). The growth evolution of the nanopillars, providing the (0001)(NP) ∐ (0001)(ZNO grain) ∐ (100)(Si surface) epitaxial relationship, is extensively studied by scanning and high resolution transmission microscopy. The approach to obtaining the ZnO 1D structures is explained in terms of selective homoepitaxial growth via the crystallographic anisotropy of the seeding layer. The advanced PL properties of ZnO NPs, e.g. indications of free excitonic and absence of defect emission, are related to their single crystalline nature within one pillar and most probably better stoichiometry and less contamination. The observed efficient monochromatic UV emission from the ZnO NPs at room temperature points toward their potential application as building blocks for nanoscale optoelectronic devices.

The effect of composition and structural ordering on the magnetism of FePt nanoparticles.

Spherical 4 nm FePt nanoparticles were synthesized by the simultaneous decomposition of Fe(CO)5 and the polyol reduction of Pt(acac)2. The final Fe-to-Pt composition was tuned between 15-55 at.% by varying the ingredient precursor ratios. The effect of composition and structural ordering on the macroscopic magnetic features of final FePt nanoparticles was examined via post-synthetic annealing stages at different conditions. Structural ordering is promoted in all cases, though samples approximating equiatomic Fe/Pt ratios eventually transform to fct-FePt phase while the FePt3-phase is favored for the Pt-richer samples. Consequently, the magnetic features of the annealed nanoparticles may be categorized; the hard magnetic FePt region dominating for Fe content between 40-55 at.% and the soft magnetic FePt3 region dominating in the region 20-30 at.% while Fe content less than 20 at.% results in Pt-richer phases with diminishing ferromagnetic behavior.

Thin film and interface properties during ZnO deposition onto high-barrier hybrid/PET flexible substrates.

The combination of transparent conductive oxides with high-barrier films deposited onto flexible polymeric substrates is of considerable importance in order to improve the efficiency, lifetime and stability of flexible electronic devices. In this work, ZnO thin films have been deposited onto high-barrier hybrid/PET flexible substrates by pulsed DC magnetron sputtering, at room temperature and by applying different power values on the target. The employment of in situ and real-time Vis-fUV (1.5-6.5 eV) spectroscopic ellipsometry allowed the investigation of the growth mechanisms of ZnO thin films as well as the modification procedure in the hybrid's surface. Island growth is dominant during the initial stages of deposition concerning low target power regime, whereas layer-by-layer deposition prevails at the high target power regime. The hybrid's modified layer of approximately 10nm was confirmed by the transmission electron microscopy measurements which additionally revealed a columnar structure of the film with a nanocrystalline morphology. The estimated size of the nanocrystals ( approximately 15 nm and above) was compatible with atomic force microscopy (AFM) measurements. Finally, the evolution of the optical parameters (energy gap and absorption peaks) of the ZnO films during the deposition was similar.

Self-assembled hexagonal ordering of Si nanocrystals embedded in SiO(2) nanodots.

Highly dense hexagonally ordered two-dimensional arrays of Si nanocrystals embedded in SiO(2) nanodots were fabricated on a silicon substrate by using a self-assembled porous anodic alumina thin film as a masking layer through which electrochemical oxidation of the Si substrate and ultralow energy Si implantation took place. After removal of the alumina film and high temperature annealing of the samples, hexagonally ordered Si nanocrystals embedded within SiO(2) nanodots were obtained, having sizes in the few tens of nanometer range. The fabricated ordered structures show significant potential for applications either in basic physics experiments or as building blocks for nanoelectronic and nanophotonic devices.

Structural, magnetic, and magneto-optical properties of nanocrystalline face centered cubic Co70Cr30/Pt multilayers with perpendicular magnetic anisotropy.

Co70Cr30 alloyed layers are combined with extremely thin Pt layers in order to produce novel face-centered-cubic multilayered films to be considered as a potential perpendicular magnetic recording medium. The films were grown on Si, glass and polyimide substrates by e-beam evaporation at a temperature slightly higher than room temperature. The multilayered structure of the films was verified by X-ray diffraction experiments. Plane-view transmission electron microscopy images have revealed the formation of very small grains in the range of 7-9 nm. Hysteresis loops as a function of temperature were recorded via the magneto-optic Kerr effect in the polar geometry configuration. The system exhibits perpendicular magnetic anisotropy, which enhances with decreasing temperature. Hysteresis loops with a squareness of 1 and a coercivity of 1.45 kOe were obtained at 10 K. Furthermore, complete magneto-optic spectra of the films are recorded, showing a strong magneto-optic enhancement in the ultraviolet region at around 4.5 eV.

Well-orientated cubic boron nitride nanocrystals as studied by high-resolution transmission electron microscopy.

In a boron nitride thin film, grown on a Si (100) substrate by radio frequency magnetron sputtering, a striking nanostructure is observed by high-resolution transmission electron microscopy. It consists of cubic boron nitride nanocrystals with a rather good triangular shape, pointing always to the substrate. The nanocrystals are usually highly defected and present their own interesting internal structure. Texture formation is observed within a nanocrystal, with all the subgrains observed to have a common <011> axis, which is also approximately parallel to a <011> axis of the Si substrate, i.e. the nanocrystals are very well structurally orientated in relation to the Si substrate (self-organized). Dislocations and stacking faults are also found in the nanocrystals.

Structural models for twin interfaces in Pd thin films.

In a Pd thin film grown on a 6H-SiC (0001) substrate, several twin interfaces have been observed, classified as (1) {111}Sigma = 3 twin interfaces and (2) {221}Sigma = 3 twin interfaces. The first ones are coherent twin interfaces and in some cases exhibit steps of one or more atomic layers in height. The second ones are perpendicular to the first ones. They usually appear with a rigid-body displacement, but in some cases no displacement was observed. Models for the interfaces are proposed.

Impairment of anorectal function in diabetes mellitus parallels duration of disease.

PURPOSE: The aim of this study was to investigate any possible relation between the severity of anorectal dysfunction in diabetes mellitus and duration of disease and presence of microangiopathy or neuropathy or both. METHODS: Standard multiport anorectal manometry was performed in 25 healthy control subjects (10 males; age (mean +/- 1 standard deviation), 62 +/- 14 years) and 38 patients with diabetes mellitus. Patients were divided into two groups according to the duration of the disease: Group A (19 patients) with a duration less than 10 years (7.2 +/- 2.5; 8 males; age, 57 +/- 18) and Group B (19 patients) with a duration longer than 10 years (19.8 +/- 5.6; 6 males; age, 62 +/- 15). RESULTS: Results are reported as mean +/- one standard deviation. Patients showed lower resting and squeeze anal pressures (P < 0.01), impaired rectoanal inhibitory and anocutaneous reflexes, and reduced sensitivity in rectal distention (P = 0.004) as compared with controls. In addition, Group B showed a significantly increased incidence of microangiopathy (P = 0.04) and autonomic and peripheral neuropathy (P = 0.002), significantly reduced basal and squeeze anal pressures (52 +/- 16 vs. 64 +/- 24 mmHg; P = 0.03 and 98 +/- 39 vs. 124 +/- 54 mmHg; P = 0.04, respectively), reduced amplitude of slow waves (7.3 +/- 3 ts. 9.5 +/- 3.7 mmHg; P = 0.03), anal leak in smaller rectal volumes (P = 0.003), and reduced response of the anal sphincter at the anocutaneous reflexes (29 +/- 14 vs. 39 +/- 14 mmHg; P = 0.05) compared with Group A. The former group of patients exhibited a significantly higher incidence of fecal incontinence (P = 0.008). CONCLUSION: Patients with long-standing diabetes mellitus have increased incidence of fecal incontinence and severely impaired function of both the anal sphincters and the rectum. These findings could be attributed to the increased incidence of microangiopathy and autonomic and peripheral neuropathy observed in this subset of diabetic patients.

Gallbladder fasting volume is reduced and gallbladder postprandial emptying is enhanced by intravenous erythromycin.

It has been recently shown that erythromycin, a macrolide antibiotic, exhibits prokinetic properties, by enhancing gastric emptying in health and disease and by inducing gallbladder contraction. The aim of the study was to further investigate the effect of intravenous erythromycin on gallbladder motility during fasting and postprandial states. In 10 healthy male subjects gallbladder emptying was assessed by ultrasonography on three different occasions, each in a random sequence, as follows: (1) after giving 300 ml of fresh milk and infusing normal saline as placebo (postprandial emptying), (2) after infusing 200 mg of erythromycin during the fasting state, and (3) after infusing 200 mg of erythromycin along with ingestion of 300 ml of fresh milk. Infusion of erythromycin and placebo lasted 10 min. From the emptying curves, the duration of the lag phase of emptying, the ejection fraction of emptying, and the time by which maximal emptying was achieved were calculated. Infusion of erythromycin induced an immediate contraction [lag phase (+/-SD): 1.3+/-2.6 SD min] of the gallbladder by 42.1+/-22% of its initial volume. Infusion of erythromycin during the postprandial state significantly decreased the duration of the lag phase (1.3+/-3.5 min after erythromycin plus test meal versus 3.6+/-4.2 min after test meal only, P < 0.04) and significantly increased the ejection fraction (78+/-8.5% after erythromycin plus test meal versus 60.6+/-8.5% after test meal only, P < 0.0008). It is concluded that intravenously given erythromycin induces contraction of the gallbladder during the fasting state and enhances postprandial gallbladder emptying by accelerating the initiation and increasing the extent of emptying.