Adsorption of mercaptopropionic acid onto Au(1 1 1): Part I. Adlayer formation, structure and electrochemistry

The adsorption of 3-mercaptopropionic acid (MPA) on Au(1 1 1) in 0.1 M H₂SO₄ was studied by cyclic voltammetry, capacitance measurements and in situ scanning tunneling microscopy (STM). The formation of a self-assembled monolayer under electrochemically controlled conditions was monitored for the first time with an STM. A two-step adsorption process has been found, beginning with the adsorption of MPA to form a disordered film, which lifts the () reconstruction of Au(1 1 1), followed by an ordering of the MPA adlayer into two different dense structures. Concomitantly with the second step, formation of the well-known vacancy islands is observed. This formation is explained by an adsorbate-induced compression of the gold substrate. Two distinctly different structures of the dense MPA monolayer on Au(1 1 1) were observed. One () structure with p=3.6-4.8 and a second structure consisting of two unit cells of () and () symmetry. In part II, the effect of the MPA on the copper electrodeposition onto Au(1 1 1) is discussed.     

Analysis of an Adaptive Selective-Reject Scheme in Time-Varying Channel with Non-Negligible Round-Trip Delay and Erroneous Feedback

In this article, an adaptive SR ARQ scheme is analyzed and optimized in a time-varying channel environment with unreliable feedback. To have an operational scheme, we choose the smaller packet size to be half of the bigger one. Thus, there is only one independent design parameter related to packet size. The other two parameters are associated with channel sensing. The performance of the adaptive scheme is measured by its average throughput, which is upper-bounded by the throughput of the so-called ideal adaptive scheme. This upper bound is very useful in the optimization of the packet size and other design parameters.     

Assemblies of concanavalin A onto carboxymethylcellulose

The immobilization of Concanavalin A, (Con A), onto flat surfaces formed by ultrathin films of carboxymethylcellulose, CMC, silicon wafers or spin-coated poly(methyl methacrylate), (PMMA), was studied by ellipsometry, contact angle measurements and atomic force microscopy (AFM). The formation of Con A monolayer was only observed onto CMC films. The adsorption constant of Con A onto CMC films was determined as being (2.1+/-0.2) x 10(6) L mol(-1). After assembling Con A onto CMC surfaces, these became more hydrophobic, indicating a molecular orientation of Con A hydrophilic residues to the polysaccharide and Con A hydrophobic residues to the air. The affinity of Con A for hydroxyl rich silicon surfaces or for more hydrophobic PMMA films was very weak, evidencing that nonspecific interactions play a marginal role. For comparison, the immobilization of Con A onto hybrid particles of PMMA/CMC was investigated by means of UV-spectrophotometry. Such particles carry CMC chains attached to the surface, as evidenced by mean zeta potential value of -40 mV. The adsorption constant determined for Con A onto PMMA/CMC particles was one order of magnitude smaller than that found for Con A onto CMC films. This finding indicates that the substrate geometry might influence the molecular arrangement of sugar residues on the surface, consequently affecting the sugar-Con A interaction (cluster effect).     

Chemische Zusammensetzung und Kristallstruktur von Sondercarbiden in warmfesten Cr-Mo- und Cr-Mo-V-Stählen

Entwicklung eines Probentisches, mit dessen Hilfe Untersuchungen von saumförmigen Sondercarbideutektoiden warmfester Cr-Mo- und Cr-Mo-V-Stähle sowie einiger Versuchsschmelzen durchgeführt wurden. Bestimmung von Gitterkonstanten.     

A procedure to determine the water-binding capacity of meat trimmings for cooked sausage formulation

Eight bovine muscles were evaluated to determine if perimysium thickness (PT) differed among muscles and carcasses and was affected by electrical stimulation (ES). In addition, the effect of PT on Warner-Bratzler shear (WBS) of steaks divided into tenderness groups was evaluated. Muscle and carcass affected (P<0.05) PT, but PT was not significantly affected by ES. Correlation coefficients revealed that PT would be a poor indicator of WBS when used alone (r=0.13). When analyzed within electrical stimulation treatment, PT was correlated (P<0.05) to WBS of NES (r=0.21) carcasses and not significantly related to WBS of ES carcasses. Within tenderness groups, PT accounted for 4.5%, 9.5%, 20.0%, and 4.0% of the variation in WBS force at 3, 7, 14, and 21 d, respectively. These results indicate that PT can be used in conjunction with other myofibrillar components of tenderness to account for some variation in WBS values of cooked beef steaks.     

Changes of the pH value of impregnated wood during exposure to wood-rotting fungi

Trametes versicolor and Schizophyllum commune). The third species was the brown-rot fungi Antrodia vaillantii, using three different strains of this species. Antrodia vaillantii substantially decreased the pH-value of impregnated and unimpregnated wood before any mass loss appeared. On the other hand, the white-rot fungus T. versicolor and S. commune caused a slight increase of the pH of impregnated and unimpregnated wood. It is suggested that a decrease of pH of wood may indicate early stages of decay by brown rot fungi.

---

Trametes versicolor und Schizophyllum commune). Die dritte Art war vom Braunf?uletyp (Antrodia vaillantii), wovon drei verschiedene St?mme eingesetzt wurden. Antrodia vaillantii senkte den pH deutlich in impr?gnierten und unbehandelten Proben, noch bevor ein Massenverlust auftrat. Die beiden Weissf?uleerreger T. versicolor und Sch. commune lie?en den pH dagegen ansteigen. Anhand des pH-Abfalls konnte man schon frühe Stadien eines Braunf?uleabbaus erkennen.

     

Combined blowing with three ‐ hole lance in a sidewall blowing converter

Traditionally, in stainless steelmaking converters, oxygen has been blown by a one‐hole lance (1 HL) and sidewall tuyères. In order to reduce the tap‐to‐tap time, the multi‐hole lance has been used for oxygen blowing. The aim of this work was to develop blowing practise for a multi‐hole lance to reduce the tap‐to‐tap time and minimise metal splashing and spitting in the sidewall blowing converter (chromium converter). In the chromium converter the chemical energy of liquid ferrochrome (which contains 4 % silicon and 7 % carbon) is utilised for scrap melting by oxidising the silicon and the part of carbon. The research has been made by a dynamically scaled water model and full‐scale converter. Used parameters were the gas flowrate from sidewall tuyères and lance, lance height, charge weight and position of multi‐hole lance. Splashing has been measured during blowing from walls (splashing) and mouth of the converter model (spitting). The model tests indicated less splashing and spitting by the three‐hole lance (3 HL) than traditional 1 HL. The 1 HL caused strong skulling of the converter cone. By 3 HL blowing the position of the lance has a remarkable effect on the direction and the amount of splashing and lance life. Because of hot metal‐slag splashes, the life time of the 3 HL was halved by position 1 (compared to 1 HL). With the lance position 2 the splashing decreased by approx. 50% in model tests and lance life time increased by ~ 50% (compared to 1 HL) in the full‐scale converter. The model agreed well with the full‐scale converter. According to the process tests, the nominal productivity of the chromium converter has increased 15 % and depending on the refining practise and the silicon content of ferrochromium the lining life has increased 20 ‐ 30 %. In the future the multi‐hole lance will be tested in the AOD vessel.