Influence of the grain structure of yttria thin films on the hydrogen isotope permeation

Steel components are required in the infrastructure and the facilities of the hydrogen economy. The high hydrogen pressures in the hydrogen economy lead to embrittlement and surface corrosion of the steels. For the functionality of the facilities it is necessary to suppress the embrittlement and the surface corrosion of the steels by protective layers, e.g. ceramic thin films. With regard to fusion power plants ceramic thin films on the structural steel materials are also required. These thin films work as a tritium permeation barrier that is necessary to prevent the loss of the radioactive fuel inventory. Oxide thin films, e.g. Al₂O₃, Er₂O₃, and Y₂O₃, are promising candidates as tritium permeation barrier layers. In terms of the application in the first wall, this is especially true for yttrium due to its favorably short decay time after neutron activation compared to the other candidates. The Y₂O₃ layers with thicknesses of 0.5 μm–1 μm are deposited on both substrate sides by RF magnetron sputter deposition. Since the microstructure of the barrier layer plays an important role for the permeation reduction, layers with three different magnetron process modes and thus three different microstructures are prepared. After annealing the cubic crystal structure of all thin films is verified by X-ray diffraction and the different microstructures are investigated by scanning electron microscopy and transmission electron microscopy. The Y₂O₃ stoichiometry of all thin films and a chromium oxide material segregation at the interface are verified by analysis methods such as X-ray photoelectron spectroscopy. The permeation reduction factors of all thin films are determined in gas-driven deuterium permeation experiments. Corresponding to the three different microstructures, reduction factors of 25, 45, and 1100 are identified. Thus, the permeation reduction is strongly dependent on the Y₂O₃ microstructure. The measurement results suggest that a high density of grain boundaries leads to a high hydrogen permeation.     

Effect of citric acid, citrate and slight a(w) decreases on the bacteriological stability of Hague liver sausage

Combinations of citric acid and citrate, with several carbohydrates and KCl, were tested in a canned Hague liver sausage model for their antimicrobial properties. pH values for the test products ranged from 5·38 to 6·48; a(w) values varied from 0·960 to 0·977. Before pasteurization, the sausage doughs were contaminated with mixtures of bacterial spores. Since the bacteriological stability sometimes appeared to be considerably improved, heated packages were challenged by incubation at 20° and 30°C; some of them for up to 2 years. Incubated packages from the standard formulation spoiled at 30°C within 3 days. Starting from this point, products with a variable, but increased, bacteriological stability were obtained. For the best stabilized batches, first symptoms of spoilage were observed after periods of incubation at 30°C, ranging from 49 to 150 days. Combinations of pH and a(w) values which can be relied upon to yield stable products consistently, cannot be derived from the accumulated data. Citric acid appeared a far more effective stabilizer than its salt. If we regard the undissociated citric acid concentration for these products (a(w) 0·960-0·972) as a significant parameter, values above approximately 13 μmkg(-1), yielded products with remarkable bacteriological stability.     

The potential of vancomycin-resistant enterococci to persist in fermented and pasteurised meat products

Experiments with 148 isolates of vancomycin-resistant enterococci (VRE) were performed to assess their potential to persist and grow in fermented sausages and pasteurised meat products. All strains were meat isolates and Van-type A, except a single VanC1 strain. In total, 143 strains of Enterococcus faecium were involved. Eight selected strains were examined for their potential to grow at high salt and nitrite levels and at reduced pH. The same isolates were used in experiments with fermented sausages. All available strains were subjected to heating tests in meat suspensions with added curing ingredients. All but one of the eight tested isolates grew at pH 4.0 in tryptone soya broth (TSB). With the combination of 8% w/w NaCl, 400 ppm NaNO2 and 0.5% w/w glucose in the meat suspension, all isolates grew at 37 degrees C, whereas none grew at 7 degrees C even after 56 days. With the addition of 10% w/w NaCl, 200 ppm NaNO2 and 0.5% w/w glucose, still one E. faecium isolate grew at 37 degrees C, although very slowly. Overall, the strains tolerated high salt and nitrite concentrations and reduced pH very well, even beyond levels applied in the regular production of fermented and/or pasteurised meat products. The tested strains could be isolated after the fermentation and further ripening of "boerenmetworst" and "snijworst". Overall, their colony counts decreased on average about 1 log-unit over a period of 60 days after batter manufacture. All 148 isolates demonstrated a relatively weak thermal resistance compared to results for selected vancomycin-sensitive enterococci strains reported in the literature and to results collected under identical experimental conditions in this laboratory. None of the strains (log inoculation level about 5-6 ml(-1) for each isolate) could be cultured after heating at 70 degrees C for 10 min.     

Determination of the eutectic solubility lines of the ternary system NaHCO3–Na2CO3–H2O

A crystallizer was built and a procedure developed to accurately measure the eutectic solubility lines where ice and salt coexist in equilibrium with the solution, for potential application of Eutectic Freeze Crystallization. The eutectic solubility lines of the ternary system NaHCO₃–Na₂CO₃–H₂O were determined experimentally and calculated with the extended UNIQUAC model. The extended UNIQUAC model describes the experimental data quite well. Anhydrous NaHCO₃ and Na₂CO₃·10H₂O were the only two types of crystals present in equilibrium with ice crystals in the ternary system. At the quadruple point NaHCO₃ and Na₂CO₃·10H₂O are in equilibrium with a solution of about 4.34 wt% of Na₂CO₃ and 4.77 wt% of NaHCO₃ at −3.32 °C. The anhydrous NaHCO₃ crystals were needle shaped with lengths between 5 and 10 μm, that were agglomerated into particles of about 100–300 μm, while the Na₂CO₃·10H₂O crystals were hexagonally shaped with sizes between 100 and 500 μm.     

The cognitive, subjective, and physical effects of a ginkgo biloba/panax ginseng combination in healthy volunteers with neurasthenic complaints

We evaluated the effects of a Ginkgo biloba/ginseng combination on cognitive function in this 90-day, double-blind, placebo-controlled, parallel-group study. Sixty-four healthy volunteers (aged 40 to 65 years), selected on the basis of fulfilling the ICD-10 F48.0 criteria for neurasthenia, were assigned randomly to four equal dosing groups, receiving 80, 160, or 320 mg of the combination b.i.d. or placebo. Assessments were performed on the day before dosing, and again at Days 1, 30, and 90 at 1 hour after the morning dose and 1 hour after the afternoon dose. The assessments included the Cognitive Drug Research (CDR) computerized assessment system, the Vienna Determination Unit, cycle ergometry, and various questionnaires. The treatments were well tolerated by all volunteers. On Day 90 at 1 hour post morning dosing, dose-related improvements were seen on the CDR tests, the 320 mg dose being significantly superior to placebo. These effects, however, were reversed 1 hour after the afternoon dose, possibly suggesting that a longer inter-dosing interval would be preferable. The 80-mg dose produced a significant benefit on the ergometry assessment of heart rate at maximum load. There were also several supporting changes from other assessments, including an advantage of 320 mg over placebo on the global score from the Symptom Checklist-90-revised (SCL-90-R) at Day 90.     

Orienting MoS2 flakes into ordered films

Layered transition metal di-chalcogenide (TMD) materials exhibit a unique combination of structural anisotropy combined with rich chemistry that confers controllability over physical properties such as bandgap and magnetism. Most research in this area is focused on single layers that are technologically challenging to produce, especially when trying to dope and alloy the host lattice. In this work, we use MoS₂ flakes as a model system for the production of deliberately oriented films for practical applications in which anisotropic materials are required. The proposed production method combines ball milling with exfoliation in solution of MoS₂ flakes, followed by their arrangement on a large centimeter-scale substrate by a simple and non-expensive procedure. The results show that the level of orientation achieved using the proposed system is as good as that of materials that were pressed and subjected to thermal treatment. The ball milling and exfoliation processes maintain the original crystalline structure of the MoS₂ flakes, and the XRD results show that additional crystallographic phases were not produced. Lattice parameters are preserved, which verifies that other species such as water molecules did not intercalate into the MoS₂ molecules. The proposed method of producing oriented films is universal, and as such, it is useful both for pure materials and for mixtures of compounds, the latter of which can be used to produce films with specifically tailored physical properties.     

Towards a better understanding of the pectin structure-function relationship in broccoli during processing: Part I—macroscopic and molecular analyses

To investigate the structure-function relationship of pectin during (pre)processing, broccoli samples (Brassica oleracea L. cultivar italica) were subjected to one of the following pretreatments: (i) low-temperature blanching (LTB), (ii) LTB in combination with Ca²⁺ infusion, (iii) high-pressure pretreatment (HP), (iv) HP in combination with Ca²⁺ infusion, or (v) no pretreatment (control sample), whether or not in combination with a thermal treatment of 15 min at 90 °C. The macroscopic attributes of broccoli were linked to the chemical structure of broccoli pectin. By enhancing the cross-linking of pectic polymers, both LTB and HP reduced the texture loss that occurred during thermal processing of broccoli. During these pretreatments, homogalacturonan was de-esterified by pectin methylesterase, which led to changes in pectin solubility. When LTB or HP was combined with Ca²⁺ infusion, changes in the structure of pectin occurred, however not always reflected at the macroscopic level. The degree of esterification of pectin in Ca²⁺-soaked broccoli samples was lower compared to non-Ca²⁺-soaked samples and, in addition, a higher amount of ionically cross-linked pectin was retrieved.     

Simplified appendectomy without stump embedding. Experiences of 20 years conventional and 5 years laparoscopic application

Since 1975, the Department of Surgery in the Grevenbroich Community Hospital (Germany) has applied a simplified technique of open appendectomy. The inhouse modified procedure without stump embedding has been performed in 3,448 cases to date. The same approach has been used in 1,463 laparoscopic appendectomies since 1991. In the laparoscopic procedure the stump is ligated solely with Roeder's loop. None of the 4,911 patients who have undergone either open or laparoscopic appendectomy have developed stump inadequacy or stercoral fistulae. According to the special literature, the complication rate after appendectomies without stump embedding is lower than that after standard procedures. In retrospect, laparoscopic appendectomy with simple ligation has confirmed the results achieved with simple ligation in open appendectomies. The technique should therefore become more common practice in open appendectomies, as well.