Effects of Sr/Ti-ratio in SrTiO3-based SOFC anodes investigated by the use of cone-shaped electrodes

In this work the A-site deficiency limit for undoped SrTiO₃, calcined in air or reducing atmosphere, was investigated. XRD and SEM analyses showed that when using the solid-state synthesis route it was difficult to achieve any A-site deficiency. Even very small deviations from unity in the Sr/Ti-ratio resulted in impurity phases. The effects of Sr/Ti-ratio on the performance of SrTiO₃ anodes for solid oxide fuel cells (SOFCs) was investigated by impedance spectroscopy with cone-shaped electrodes. The electrocatalytic activity of the SrTiO₃ cone samples, with various amount of reduced titanium dioxide phases (Magnéli phases), was investigated for oxidation of H₂ at 700 °C. High temperature treatment at 1000 °C, between the measurements at 700 °C, showed that high content of Magnéli phases leads to faster degradation of the activity. The suitability for using cone-shaped electrodes as a tool for investigating electrode materials is discussed.     

Characterization of Ce0.9Gd0.1O1.95 powders synthesized by spray drying

Ce_0.9Gd_0.1O_1.95 powders were synthesized by spray drying and successive calcinations. The phase purity, BET surface area, and particle morphology of as-sprayed and calcined powders were characterized. After calcination above 300 °C, the powders were single phase and showed a BET surface area of 68 m²/g when calcined at 300 °C. The conductivity, in air, of sintered pellets was measured by electrochemical impedance spectroscopy (EIS) and it was found to be comparable with literature values. The activation energy for the total conductivity was around 0.83 eV. The powder calcined at lower temperature showed better sinterability and higher total conductivity due to an increased bulk conductivity.     

Decreased lumbar cerebrospinal fluid levels of monoamine metabolites in vascular dementia

The levels of the monoamine metabolites 5-hydroxy-indoleacetic acid (5-HIAA), homovanillic acid (HVA), and 4-hydroxy-3-methoxy-phenylglycol (HMPG) were determined in lumbar cerebrospinal fluid (CSF) of 56 patients with vascular dementia (VAD) and 57 healthy controls. Despite CSF sampling under standardized conditions, the variability in values was wide among both patients and controls. This suggests that yet unknown factors affect the lumbar CSF concentrations of monoamine metabolites. The VAD group showed significantly lower mean concentrations of 5-HIAA (p < .001) and HVA (p < .001) than the control group. These low concentrations appear to be no disease-specific phenomenon, but may be attributable to subcortical white-matter changes or a decreased production of monoamines, which are dependent on oxygen for their synthesis.     

Origin of nondisjunction in trisomy 8 and trisomy 8 mosaicism

OBJECTIVES: This study explores reactions to low-level chemical challenge, aiming at the development of test procedures for assessing individual sensitivity to smells and chemicals. METHODS: Subjects with symptoms and neuropsychological test results compatible with toxic encephalopathy type 2A (TE-2A) and 2B (TE-2B) and unexposed referents (N=12 in each group) were challenged in an exposure chamber. Toluene exposure was started at 11 mg/m3, and it followed a geometric progression scale with a ratio of 2, until reaching 180 mg/m3. In a counterbalanced design, the subjects were similarly exposed to n-butyl acetate starting at a concentration of 14 mg/m3 and increasing to 228 mg/m3. At each exposure level, smell intensity was measured on a 7-step category scale. Mucous membrane irritation and annoyance reactions were rated on visual analogue scales. RESULTS: Both TE groups showed high sensitivity to the low-level solvent challenge, which provoked immediate annoyance and fatigue reactions. In particular the TE-2B group related smell intensity to various annoyance dimensions during exposure to n-butyl acetate, a pattern not observed during toluene exposure. The reference group clearly separated smell intensity and annoyance reactions in both exposure conditions. CONCLUSIONS: The reaction of the TE cases suggests that chemical sensitivity can be distinguished from normal annoyance reactions by the inability to differentiate between smell intensity and an experience of irritation from mucous membranes in air concentrations well below the trigeminal irritation threshold level. Fatigue coreactivity in challenges to single substances below the neurotoxic level may also be important.     

Mass Spectrometric Analysis of Cerebrospinal Fluid Ubiquitin in Alzheimer's Disease and Parkinsonian Disorders

1 Purpose

Dysfunctional proteostasis, with decreased protein degradation and an accumulation of ubiquitin into aggregated protein inclusions, is a feature of neurodegenerative diseases. Identifying new potential biomarkers in cerebrospinal fluid (CSF) reflecting this process could contribute important information on pathophysiology.

2 Experimental design

A developed method combining SPE and PRM‐MS is employed to monitor the concentration of ubiquitin in CSF from subjects with Alzheimer's disease (AD), Parkinson's disease (PD), and progressive supranuclear palsy (PSP). Four independent cross‐sectional studies are conducted, studies 1–4, including controls (n = 86) and participants with AD (n = 60), PD (n = 15), and PSP (n = 11).

3 Results

The method shows a repeatability and intermediate precision not exceeding 6.1 and 7.9%, respectively. The determined LOD is 0.1 nm and the LOQ range between 0.625 and 80 nm . The CSF ubiquitin concentration is 1.2–1.5‐fold higher in AD patients compared with controls in the three independent AD‐control studies (Study 1, p < 0.001; Study 2, p < 0.001; and Study 3, p = 0.003). In the fourth study, there is no difference in PD or PSP, compared to controls.

4 Conclusion and clinical relevance

CSF ubiquitin may reflect dysfunctional proteostasis in AD. The described method can be used for further exploration of ubiquitin as a potential biomarker in neurodegenerative diseases.     

Chemical synthesis of a dual branched malto-decaose: a potential substrate for alpha-amylases

A convergent block strategy for general use in efficient synthesis of complex alpha-(1-->4)- and alpha-(1-->6)-malto-oligosaccharides is demonstrated with the first chemical synthesis of a malto-oligosaccharide, the decasaccharide 6,6'-bis(alpha-maltosyl)-maltohexaose, with two branch points. Using this chemically defined branched oligosaccharide as a substrate, the cleavage pattern of seven different alpha-amylases were investigated. Alpha-amylases from human saliva, porcine pancreas, barley alpha-amylase 2 and recombinant barley alpha-amylase 1 all hydrolysed the decasaccharide selectively. This resulted in a branched hexasaccharide and a branched tetrasaccharide. Alpha-amylases from Asperagillus oryzae, Bacillus licheniformis and Bacillus sp. cleaved the decasaccharide at two distinct sites, either producing two branched pentasaccharides, or a branched hexasaccharide and a branched tetrasaccharide. In addition, the enzymes were tested on the single-branched octasaccharide 6-alpha-maltosyl-maltohexaose, which was prepared from 6,6'-bis(alpha-maltosyl)-maltohexaose by treatment with malt limit dextrinase. A similar cleavage pattern to that found for the corresponding linear malto-oligosaccharide substrate was observed.     

Physico‐chemical Characterization of Floridean Starch of Red Algae

The current work reports on isolation and physico‐chemical characterization of floridean starch from three species of agarophytic macro red algae. As determined by ¹H‐NMR spectroscopy, the average chain length and degree of branching frequency of this starch were 18 and 4.8, respectively. According to its amylopectin chain length distribution obtained by Dionex analysis, the crystalline polymorph of floridean starch from the red alga Gracilariopsis lemaneiformis was deduced to be C‐type and this was further supported from its X‐ray crystallographic pattern. Enzymatic analysis of its glucose 6‐phosphate content showed that floridean starch had a low level of covalently linked phosphate (1 nmol per milligram starch) and this was further confirmed by ³¹P‐NMR. The absorbance peak of floridean starch with iodine occurred at 527—530 nm and the blue value was low (0.1), indicating the absence of amylose, which was confirmed by differential scanning calorimetry (DSC). Floridean starch exhibited low gelatinization temperature, low viscosity, high clarity and little or no retrogradation upon repetitive freeze‐thaw cycles, as studied by DSC and rapid viscosity analysis (RVA). These results are discussed in light of the functional properties and the structure of floridean starch.     

Suppression of Fusarium graminearium growth by differently structured starch types

We investigated the growth behavior and amylolytic enzymes of Fusarium graminearum cultivated on different types of native starch granules including barley (A‐type crystalline polymorph), potato and Curcuma zedoaria (B‐type crystalline polymorph), cassava (C‐type crystalline polymorph), and high AM maize (A + Vh‐type crystalline polymorphs). F. graminearum grew poorly on B‐type starches and the accumulation of biomass was similar to that obtained for fungi cultivated under carbohydrate starvation conditions. In comparison, three‐ to fivefold higher accumulation of fungal biomass was observed for growth on the A‐, C‐ and A + Vh‐type starches. Fungal glucoamylase and α‐amylase activity increased over time in the presence of native starch granules. Interestingly, resistant B‐type starches induced the highest amylolytic activity indicating that F. graminearum interacts with B‐type granules although only limited degradation occur. Starch degradation products maltose and malto‐oligosacharides was found to increase glucoamylase and α‐amylase activity, whereas glucose acted as a catabolite repressor.     

Electric field reduction due to charge accumulation in adielectric-covered electrode system

Outlines for increased insulation performance of an air gap through the use of dielectric coatings are given. Theoretically, it is shown that the homogeneous electric field in a plane-parallel electrode system can be reduced if the electrodes are covered with a thick dielectric coating. Free charges will be affected by the electric field between the electrodes and are deposited at the dielectric surfaces. As a consequence, a counteracting electric field component results, which accordingly causes a reduction of the total electric field in the air gap and an enhancement of the field in the dielectric layers, i.e. the electric field is forced into the dielectric coatings by the charges. This effect has important implications in HV engineering. Introductory experiments supporting the idea have been carried out with promising results. It was confirmed that the withstand voltage of a plane-parallel electrode geometry with an open air gap, for dc as well as unipolar impulse voltage, could be increased considerably if the electrodes were covered with thick polymeric layers. Charge formation at the electrode surfaces as well as in the air gap is believed to be responsible for this effect. In today's insulation systems, this is known to work only for time-independent electric fields, i.e. generally dc voltages. Further experimental work is required and will be performed in order to scrutinize thoroughly and clarify the phenomenon, its capabilities and limitations