Theoretical Investigation of the Size Effect on the Oxygen Adsorption Energy of Coinage Metal Nanoparticles

Catalysis Letters - This study evaluates the finite size effect on the oxygen adsorption energy of coinage metal (Cu, Ag and Au) cuboctahedral nanoparticles in the size range of 13 to 1415 atoms...     

Tryptophan Analogues with Fixed Side-Chain Orientation: Expanding the Scope

A generalized synthetic strategy is proposed here for the synthesis of asymmetric β-indoylated amino acids by 8-aminoquinoline (8AQ)-directed C(sp³)-H functionalization of suitably protected precursors. Peptides containing one of the four stereoisomers of (indol-3-yl)-3-phenylalanine at position 2 of the parent peptide KwFwLL-NH₂ (w=d -Trp) cover a wide range of activities as ghrelin receptor inverse agonists, among them the most active described until now. This application exemplarily shows how β-indoylated amino acids can be used for the systematic variation of the position of an indole group in a bioactive peptide.     

Wedge splitting test for a steel-concrete interface

This paper presents a test method designated for the determination of the stress-crack opening relationship of a steel-concrete interface. The method is based on the well known wedge splitting test (WST), and it is illustrated how to obtain the stress-crack opening relationship through an inverse analysis. This inversion method utilizes the cracked hinge model, modified such that it describes the problem at hand. In this paper, pure concrete and steel-concrete composite specimens are tested and compared. It turns out that interfacial cracking of a bimaterial specimen usually behaves as one of the parent materials, in this case concrete. The stress-crack opening relationship of both the concrete and bimaterial specimens are obtained through the proposed inverse analysis. The results show, that interfacial cracking is dominated by the so-called wall-effect and its behavior can be described as quasi-brittle. However, due to the wall-effect, interfacial cracking is more brittle than for the pure concrete.     

Long-Term Effects of Neural Precursor Cell Transplantation on Secondary Injury Processes and Functional Recovery after Severe Cervical Contusion-Compression Spinal Cord Injury

Cervical spinal cord injury (SCI) remains a devastating event without adequate treatment options despite decades of research. In this context, the usefulness of common preclinical SCI models has been criticized. We, therefore, aimed to use a clinically relevant animal model of severe cervical SCI to assess the long-term effects of neural precursor cell (NPC) transplantation on secondary injury processes and functional recovery. To this end, we performed a clip contusion-compression injury at the C6 level in 40 female Wistar rats and a sham surgery in 10 female Wistar rats. NPCs, isolated from the subventricular zone of green fluorescent protein (GFP) expressing transgenic rat embryos, were transplanted ten days after the injury. Functional recovery was assessed weekly, and FluoroGold (FG) retrograde fiber-labeling, as well as manganese-enhanced magnetic resonance imaging (MEMRI), were performed prior to the sacrifice of the animals eight weeks after SCI. After cryosectioning of the spinal cords, immunofluorescence staining was conducted. Results were compared between the treatment groups (NPC, Vehicle, Sham) and statistically analyzed (p < 0.05 was considered significant). Despite the severity of the injury, leading to substantial morbidity and mortality during the experiment, long-term survival of the engrafted NPCs with a predominant differentiation into oligodendrocytes could be observed after eight weeks. While myelination of the injured spinal cord was not significantly improved, NPC treated animals showed a significant increase of intact perilesional motor neurons and preserved spinal tracts compared to untreated Vehicle animals. These findings were associated with enhanced preservation of intact spinal cord tissue. However, reactive astrogliosis and inflammation where not significantly reduced by the NPC-treatment. While differences in the Basso–Beattie–Bresnahan (BBB) score and the Gridwalk test remained insignificant, animals in the NPC group performed significantly better in the more objective CatWalk XT gait analysis, suggesting some beneficial effects of the engrafted NPCs on the functional recovery after severe cervical SCI.     

Theoretical Structure Determination of a Complex Material: κ-Al2O3

The atomic and electronic structures of kappa-Al₂O₃ are determined using theoretical first-principles techniques based on density-functional theory (DFT), plane waves, and pseudopotentials. The obtained structure is confirmed by analysis of powder X-ray diffraction data. The structure is orthorhombic with oxygen ions in close-packed ABAC stacking and aluminum ions occupying both tetrahedral (1/4) and octahedral (3/4) interstitial sites. A growth model for chemical vapor deposition of kappa-Al₂O₃ is proposed based on the atomic structure. Calculated electronic structure and charge density yield a band gap of 5.3 eV and a high ionic character of the bonds. The study shows the applicability of DFT-based methods to complex and metastable materials.     

Influence of Feed Composition and Drying Parameters on the Surface Composition of a Spray-Dried Multicomponent Particle

Surface properties of multicomponent particles produced in spray drying can be controlled by selective accumulation of specific components, which are present in the liquid feed, on the particle surface. Such modification of the surface composition can take place only before a solid shell forms on the particle surface. In this contribution, the influence of the concentration of surface active component on modifications of the surface composition is discussed. Based on results of single-droplet drying simulations, changes in the concentration of the surface active component at the solution-air interface are related to the composition of spray-dried particles.     

Occurrence and removal of pharmaceuticals in a municipal sewage treatment system in the south of Sweden

The occurrence and removal rate of seven pharmaceuticals (ibuprofen, naproxen, diclofenac, fluoxetine, ofloxacin, norfloxacin, ciprofloxacin), two metabolites (norfluoxetine, clofibric acid), one degradation product (4-isobutylacetophenone) and 3 estrogens (17α-ethinylestradiol, 17β-estradiol, estrone) were studied in the inlet and outlet of a tertiary sewage treatment plant (STP) in Sweden as well as between different treatment steps in the STP which includes a conventional activated sludge step. Pharmaceuticals in raw household and raw hospital sewage streams leading to the STP were as well investigated. Hydraulic retention times (HRT) of each treatment step was considered for sampling and for the calculation of the removal rates. These rates were above 90%, except for diclofenac, clofibric acid, estrone and ofloxacin. However, only diclofenac and naproxen showed significant effluent loads (> 145 mg/d/1000 inh). Diclofenac was not eliminated during the treatment and in fact even higher concentrations were found at the effluent than in the inlet of the STP. 17α-Ethinylestradiol was not detected in any of the samples. Results indicate that a STP such as the one in Kristianstad, Sweden, with a tertiary treatment is sufficient to remove significantly most of the investigated pharmaceuticals. The chemical treatment improved the removal of several pharmaceuticals especially the antibiotics, which showed step removal rates between 55 and 70%. The expected concentration levels of the pharmaceuticals in the surface water (dilution 1 to 10) close to the outlet of the STP are below the no-observed effect-concentration (NOEC). However, despite that this would imply no important effects in the aquatic environment one cannot rule out negative consequences nearby the STP because most of the NOEC values are derived from acute toxicity data. This may underestimate the real impact of pharmaceuticals in the aquatic ecosystem.     

Andrena wilkella male bees discriminate between enantiomers of cephalic secretion components

Diastereomers of the spiroacetal, 2,8-dimethyl-1,7-dioxaspiro [5.5]undecane, represent main components of the cephalic secretion from males of the solitary bee,Andrena wilkella. The major compound proved to be of high enantiomeric purity, showing (2S,6R,8S) configuration. Only the naturally occurring enantiomer attracted patrolling males in the field; its antipode was behaviorally inactive and in a racemic mixture did not inhibit response. The (E,Z) diastereomers were also found to be almost inactive. EAG studies gave the same result as the behavioral tests. The biological function of the spiroacetal is discussed in view of the evolution of the mating behavior inA. wilkella.     

Shaping frequency-dependent time resolution when estimatingspectral properties with parametric methods

The problem of tracking time-varying properties of a signal is studied. The somewhat contradictory notion of “time-varying spectrum” and how to estimate the “current” spectrum in an on-line fashion is discussed. The traditional concepts and relations between time and frequency resolution are crucial for this problem. We introduce two definitions for the time resolution of filters, essentially measuring the effective number of past data that are used to form the estimate. In, for example, wavelet transform techniques, frequency-dependent time resolutions are used so that fewer data are used at higher frequencies, thus enabling faster tracking of high-frequency components (at the price of worse frequency resolution). The main contribution of the paper is to show how this same feature can be introduced when estimating spectra via a time-varying, autoregressive model of the signal. This is achieved by a special choice of nominal covariance matrix for the underlying parameter changes     

Emotions, defenses, coping mechanisms, and symptoms.

Used L. A. Gottschalk and G. C. Gleser's (1969) method of content analysis to examine 5-min samples of speech elicited from 6 different groups of Ss: 30 young normal men (mean age 25.7 yrs), 30 normative adults (aged 20–50 yrs), 30 normative schoolchildren (aged 6–26 yrs), 20 adults with psychoneuroses, 44 emotionally disturbed criminal offenders (mean age 25.6 yrs), and 22 acute schizophrenics (aged 21–55 yrs). Ss were given purposely ambiguous standardized instructions simulating the request to free-associate. Findings indicate that displacements and denials in mentally healthy individuals are more likely to function as coping mechanisms in contrast to their function as defenses or symptoms in mentally disordered people. No significant effects of sex, age, intelligence, or state of consciousness were found. (PsycINFO Database Record (c) 2010 APA, all rights reserved)