The effect of ‘natural’ defects on leather dyeing

Dyeing leather is very different from dyeing textiles, not least because of the defects that are frequently present on the skins. Axel Landmann looks at the many defects that can occur, and how they affect the dyeing process.     

Deconvolution improves colocalization analysis of multiple fluorochromes in 3D confocal data sets more than filtering techniques

Background and noise impair image quality by affecting resolution and obscuring image detail in the low intensity range. Because background levels in unprocessed confocal images are frequently at about 30% maximum intensity, colocalization analysis, a typical segmentation process, is limited to high intensity signal and prone to noise‐induced, false‐positive events. This makes suppression or removal of background crucial for this kind of image analysis. This paper examines the effects of median filtering and deconvolution, two image‐processing techniques enhancing the signal‐to‐noise ratio (SNR), on the results of colocalization analysis in confocal data sets of biological specimens. The data show that median filtering can improve the SNR by a factor of 2. The technique eliminates noise‐induced colocalization events successfully. However, because filtering recovers voxel values from the local neighbourhood false‐negative (‘dissipation’ of signal intensity below threshold value) as well as false‐positive (‘fusion’ of noise with low intensity signal resulting in above threshold intensities), results can be generated. In addition, filtering involves the convolution of an image with a kernel, a procedure that inherently impairs resolution. Image restoration by deconvolution avoids both of these disadvantages. Such routines calculate a model of the object considering various parameters that impair image formation and are able to suppress background down to very low levels (< 10% maximum intensity, resulting in a SNR improved by a factor 3 as compared to raw images). This makes additional objects in the low intensity but high frequency range available to analysis. In addition, removal of noise and distortions induced by the optical system results in improved resolution, which is of critical importance in cases involving objects of near resolution size. The technique is, however, sensitive to overestimation of the background level. In conclusion, colocalization analysis will be improved by deconvolution more than by filtering. This applies especially to specimens characterized by small object size and/or low intensities.     

Alanine Scan of the Peptide Antibiotic Feglymycin: Assessment of Amino Acid Side Chains Contributing to Antimicrobial Activity

The antibiotic feglymycin is a linear 13‐mer peptide synthesized by the bacterium Streptomyces sp. DSM 11171. It mainly consists of the nonproteinogenic amino acids 4‐hydroxyphenylglycine and 3,5‐dihydroxyphenylglycine. An alanine scan of feglymycin was performed by solution‐phase peptide synthesis in order to assess the significance of individual amino acid side chains for biological activity. Hence, 13 peptides were synthesized from di‐ and tripeptide building blocks, and subsequently tested for antibacterial activity against Staphylococcus aureus strains. Furthermore we tested the inhibition of peptidoglycan biosynthesis enzymes MurA and MurC, which are inhibited by feglymycin. Whereas the antibacterial activity is significantly based on the three amino acids D ‐Hpg1, L ‐Hpg5, and L ‐Phe12, the inhibitory activity against MurA and MurC depends mainly on L ‐Asp13. The difference in the position dependence for antibacterial activity and enzyme inhibition suggests multiple molecular targets in the modes of action of feglymycin.     

Involvement of GPx-3 in the Reciprocal Control of Redox Metabolism in the Leukemic Niche

The bone marrow (BM) microenvironment plays a crucial role in the development and progression of leukemia (AML). Intracellular reactive oxygen species (ROS) are involved in the regulation of the biology of leukemia-initiating cells, where the antioxidant enzyme GPx-3 could be involved as a determinant of cellular self-renewal. Little is known however about the role of the microenvironment in the control of the oxidative metabolism of AML cells. In the present study, a coculture model of BM mesenchymal stromal cells (MSCs) and AML cells (KG1a cell-line and primary BM blasts) was used to explore this metabolic pathway. MSC-contact, rather than culture with MSC-conditioned medium, decreases ROS levels and inhibits the Nrf-2 pathway through overexpression of GPx3 in AML cells. The decrease of ROS levels also inactivates p38MAPK and reduces the proliferation of AML cells. Conversely, contact with AML cells modifies MSCs in that they display an increased oxidative stress and Nrf-2 activation, together with a concomitant lowered expression of GPx-3. Altogether, these experiments suggest that a reciprocal control of oxidative metabolism is initiated by direct cell–cell contact between MSCs and AML cells. GPx-3 expression appears to play a crucial role in this cross-talk and could be involved in the regulation of leukemogenesis.     

Cost optimization of cross-laminated timber panels in one-way bending

European Journal of Wood and Wood Products - For the purposes of structural design, cross-laminated timber (CLT) panels are typically chosen from tables detailing standardized layups. While this is...     

Effect of a weight loss intervention on anthropometric measures and metabolic risk factors in pre- versus postmenopausal women

Background

The present study examines changes in body weight, fat mass, metabolic and hormonal parameters in overweight and obese pre- and postmenopausal women who participated in a weight loss intervention.

Methods

Seventy-two subjects were included in the analysis of this single arm study (premenopausal: 22 women, age 43.7 ± 6.4 years, BMI 31.0 ± 2.4 kg/m²; postmenopausal: 50 women, age 58.2 ± 5.1 years, BMI 32.9 ± 3.7 kg/m²). Weight reduction was achieved by the use of a meal replacement and fat-reduced diet. In addition, from week 6 to 24 participants attended a guided exercise program. Body composition was analyzed with the Bod Pod^®. Blood pressures were taken at every visit and blood was collected at baseline and closeout of the study to evaluate lipids, insulin, cortisol and leptin levels.

Results

BMI, fat mass, waist circumference, systolic blood pressure, triglycerides, glucose, leptin and cortisol were higher in the postmenopausal women at baseline. Both groups achieved a substantial and comparable weight loss (pre- vs. postmenopausal: 6.7 ± 4.9 vs 6.7 ± 4.4 kg; n.s.). However, in contrast to premenopausal women, weight loss in postmenopausal women was exclusively due to a reduction of fat mass (-5.3 ± 5.1 vs -6.6 ± 4.1 kg; p < 0.01). In premenopausal women 21% of weight loss was attributed to a reduction in lean body mass. Blood pressure, triglycerides, HDL-cholesterol, and glucose improved significantly only in postmenopausal women whereas total cholesterol and LDL-cholesterol were lowered significantly in both groups.

Conclusion

Both groups showed comparable weight loss and in postmenopausal women weight loss was associated with a pronounced improvement in metabolic risk factors thereby reducing the prevalence of metabolic syndrome.     

Design and application of a freeze-fracture stage with a cleaver device for Balzers ‘freeze-etching’ apparatus

A fracturing mechanism in the form of a double-wedged cleaver, used previously on other freeze-fracture machines, has been incorporated in the Balzers BAF 400 D apparatus. The design of the stage, with the cleaver, is explained and its performance and advantages are outlined. By minimizing mechanical damage to the exposed surface of the frozen specimen and reducing contamination by effective shrouding, an improvement in the quality of the replicas is achieved. The suitability of this mechanism for the fracturing of tough tissues such as skin is also outlined.     

Using grounded theory as a method for rigorously reviewing literature

This paper offers guidance to conducting a rigorous literature review. We present this in the form of a five-stage process in which we use Grounded Theory as a method. We first probe the guidelines explicated by Webster and Watson, and then we show the added value of Grounded Theory for rigorously analyzing a carefully chosen set of studies; it assures solidly legitimized, in-depth analyses of empirical facts and related insights. This includes, the emergence of new themes, issues and opportunities; interrelationships and dependencies in or beyond a particular area; as well as inconsistencies. If carried out meticulously, reviewing a well-carved out piece of literature by following this guide is likely to lead to more integrated and fruitful theory emergence, something that would enrich many fields in the social sciences.     

Can tutors be supported in giving effective explanations?

Tutors often make use of explanations that do not promote learning. One reason for the ineffectiveness of explanations might lie in tutors' failure to take into account a tutee's understanding in order to individualize instruction. To test whether tutors provide more effective explanations when they are assisted in assessing a tutee's understanding, we conducted an experiment (N = 30 dyads of tutors and tutees) and varied whether tutors received information about a tutee's individual knowledge level. Results showed that only tutors provided with information about the tutee were able to customize instruction. As a consequence, the individualized explanations lowered the incidence of clarifying questions on the part of the tutees, deepened their understanding, and reduced the number of false beliefs about newly learned concepts. The findings suggest that a diagnosis-based approach to support tutors in developing a model of the tutee effectively contributes to the individualization of instruction in tutoring. (PsycINFO Database Record (c) 2010 APA, all rights reserved)