Spatial Micropatterning of Growth Factors in 3D Hydrogels for Location‐Specific Regulation of Cellular Behaviors

Growth factors are potent stimuli for regulating cell function in tissue engineering strategies, but spatially patterning their presentation in 3D in a facile manner using a single material is challenging. Micropatterning is an attractive tool to modulate the cellular microenvironment with various biochemical and physical cues and study their effects on stem cell behaviors. Implementing heparin's ability to immobilize growth factors, dual‐crosslinkable alginate hydrogels are micropatterned in 3D with photocrosslinkable heparin substrates with various geometries and micropattern sizes, and their capability to establish 3D micropatterns of growth factors within the hydrogels is confirmed. This 3D micropatterning method could be applied to various heparin binding growth factors, such as fibroblast growth factor‐2, vascular endothelial growth factor, transforming growth factor‐betas and bone morphogenetic proteins while retaining the hydrogel's natural degradability and cytocompability. Stem cells encapsulated within these micropatterned hydrogels have exhibited spatially localized growth and differentiation responses corresponding to various growth factor patterns, demonstrating the versatility of the approach in controlling stem cell behavior for tissue engineering and regenerative medicine applications.     

Whither High-temperature Steaming ?

Recent advances in machinery design have led to the development of high-temperature festoon steamers for the fixation of prints on woven or knitted fabrics made from flat or texturised yarns. Dye selection for polyester, polyester-cellulosic blends, triacetate and secondary acetate fabrics is discussed, together with other possible uses of the new steamers. The preferred printing paste contains urea, but, since there are some objections to the use of urea, the validity of which depends on the conditions in a particular works, recent work is described which has led to a printing-paste recipe based on the use of Atexal PN-HT (1CI). The HT steaming process is the most rational one for the fixation of disperse dyes on synthetic-polymer fabrics.     

A Well Protected Intruder: The Effective Antimicrobial Defense of the Invasive Ladybird Harmonia axyridis

The harlequin ladybird Harmonia axyridis (Coleoptera: Coccinellidae) is a polyphagous predatory beetle native to Central and Eastern Asia. Since 2007 it has established all over Central Europe. In order to elucidate which defense strategy is responsible for its high resistance to diseases, we tested hemolymph as well as eleven main components of the headspace of H. axyridis for antimicrobial activity against Gram-positive (Bacillus subtilis, B. thuringiensis ssp. tenebrionis, Micrococcus luteus) and Gram-negative bacteria (Escherichia coli) and yeast (Saccharomyces cerevisiae). While three of the volatile compounds weakly reduced the growth of microorganisms, hemolymph of adults and larvae of H. axyridis strongly inhibited the growth of Gram-positive and Gram-negative bacteria as well as yeast. Furthermore, we compared the antimicrobial activity in the hemolymph of H. axyridis and Coccinella septempunctata. Antimicrobial activity in H. axyridis was about a thousand times higher compared to hemolymph from C. septempunctata. In contrast to C. septempunctata, the antimicrobial activity in H. axyridis was present without prior challenge. Minimal inhibitory concentration (MIC) of the hemolymph of H. axyridis was lowest against E. coli and yeast followed by B. subtilis, and was highest against entomopathogenic B. thuringiensis ssp. tenebrionidae. Furthermore, MIC values of the hemolymph obtained from live beetles were significantly lower than from frozen insects. This suggests that the active antimicrobial compound is affected by freezing and subsequent thawing of the beetles. Potential implications of our findings for the competitive advantages of H. axyridis over C. septempunctata are discussed.     

Soot Particle Studies—Instrument Inter-Comparison—Project Overview

An inter-comparison study of instruments designed to measure the microphysical and optical properties of soot particles was completed. The following mass-based instruments were tested: Couette Centrifugal Particle Mass Analyzer (CPMA), Time-of-Flight Aerosol Mass Spectrometer—Scanning Mobility Particle Sizer (AMS-SMPS), Single Particle Soot Photometer (SP2), Soot Particle-Aerosol Mass Spectrometer (SP-AMS) and Photoelectric Aerosol Sensor (PAS2000CE). Optical instruments measured absorption (photoacoustic, interferometric, and filter-based), scattering (in situ), and extinction (light attenuation within an optical cavity). The study covered an experimental matrix consisting of 318 runs that systematically tested the performance of instruments across a range of parameters including: fuel equivalence ratio (1.8 ≤ φ ≤ 5), particle shape (mass-mobility exponent ( D _fm ), 2.0 ≤ D _fm ≤ 3.0), particle mobility size (30 ≤ d _m ≤ 300 nm), black carbon mass (0.07 ≤ m _BC ≤ 4.2 fg) and particle chemical composition. In selected runs, particles were coated with sulfuric acid or dioctyl sebacate (DOS) (0.5 ≤ Δ r _ve ≤ 201 nm) where Δ r _ve is the change in the volume equivalent radius due to the coating material. The effect of non-absorbing coatings on instrument response was determined. Changes in the morphology of fractal soot particles were monitored during coating and denuding processes and the effect of particle shape on instrument response was determined. The combination of optical and mass based measurements was used to determine the mass specific absorption coefficient for denuded soot particles. The single scattering albedo of the particles was also measured. An overview of the experiments and sample results are presented.     

An examination of the mechanisms for stable foam formation in activated sludge systems

Screening pure cultures of 65 mycolic acid producing bacteria (Mycolata) isolated mainly from activated sludge with a laboratory based foaming test revealed that not all foamed under the conditions used. However, for most, the data were generally consistent with the flotation theory as an explanation for foaming. Thus a stable foam required three components, air bubbles, surfactants and hydrophobic cells. With non-hydrophobic cells, an unstable foam was generated, and in the absence of surfactants, cells formed a greasy surface scum. Addition of surfactant converted a scumming population into one forming a stable foam. The ability to generate a foam depended on a threshold cell number, which varied between individual isolates and reduced markedly in the presence of surfactant. Consequently, the concept of a universal threshold applicable to all foaming Mycolata is not supported by these data. The role of surfactants in foaming is poorly understood, but evidence is presented for the first time that surfactin synthesised by Bacillus subtilis may be important.     

Contribution of biomass burning to atmospheric polycyclic aromatic hydrocarbons at three European background sites

Radiocarbon analysis of atmospheric polycyclic aromatic hydrocarbons (PAHs) from three background areas in Sweden, Croatia, and Greece was performed to apportion their origin between fossil and biomass combustion. Diagnostic ratios of PAHs implied that wood and coal combustion was relatively more important in the northern European site, while combustion of fossil fuels was the dominant source of PAHs to the two central-southern European background sites. The radiocarbon content (delta14C) of atmospheric PAHs in Sweden ranged between -388 per thousand and -381 per thousand, while more depleted values were observed for Greece (-914 per thousand) and Croatia (-888 per thousand). Using a 14C isotopic mass balance model it was calculated that biomass burning contributes nearly 10% of the total PAH burden in the studied southern European atmosphere with fossil fuel combustion making up the 90% balance. In contrast, biomass burning contributes about 50% of total PAHs in the atmosphere at the Swedish site. Our results suggest that the relative contributions of biomass burning and fossil fuels to atmospheric PAHs may differ considerably between countries, and therefore, different national control strategies might be needed if a further reduction of these pollutants is to be achieved on a continental-global scale.     

Variable selection in discriminant partial least-squares analysis

Variable selection enhances the understanding and interpretability of multivariate classification models. A new chemometric method based on the selection of the most important variables in discriminant partial least-squares (VS-DPLS) analysis is described. The suggested method is a simple extension of DPLS where a small number of elements in the weight vector w is retained for each factor. The optimal number of DPLS factors is determined by cross-validation. The new algorithm is applied to four different high-dimensional spectral data sets with excellent results. Spectral profiles from Fourier transform infrared spectroscopy and pyrolysis mass spectrometry are used. To investigate the uniqueness of the selected variables an iterative VS-DPLS procedure is performed. At each iteration, the previously found selected variables are removed to see if a new VS-DPLS classification model can be constructed using a different set of variables. In this manner, it is possible to determine regions rather than individual variables that are important for a successful classification.     

Impact of agriculture on the built form of Al-Alkhalaf

This study is part of a comprehensive investigation of traditional settlements in the highland of Southwestern Saudi Arabia. The present study focuses on several factors which influenced the urban development of Al-Alkhalaf and its surroundings. The investigation began with the exploration of kinship systems as an underlying force that shaped the urban and economic structure of the village which is considered the principal determinant of the settlement built form and environment. The role of climate and topography in the urban and economic structure is examined, an influence highlighted by the unique pattern of agronomic, building and design techniques. The influence of Islamic and tribal laws on agricultural and building practices is investigated, a pertinent relationship which is viewed through the integration between the agricultural fields and the built form of the village, the layout of streets, open spaces, warning and defence towers, and residential areas.     

Regulation of Stem Cell Fate in a Three‐Dimensional Micropatterned Dual‐Crosslinked Hydrogel System

Micropatterning technology is a powerful tool for controlling the cellular microenvironment and investigating the effects of physical parameters on cell behaviors, such as migration, proliferation, apoptosis, and differentiation. Although there have been significant developments in regulating the spatial and temporal distribution of physical properties in various materials, little is known about the role of the size of micropatterned regions of hydrogels with different crosslinking densities on the response of encapsulated cells. In this study, a novel alginate hydrogel system that can be micropatterned three‐dimensionally is engineered to create regions that are crosslinked by a single mechanism or dual mechanisms. By manipulating micropattern size while keeping the overall ratio of single‐ to dual‐crosslinked hydrogel volume constant, the physical properties of the micropatterned alginate hydrogels are spatially tunable. When human adipose‐derived stem cells (hASCs) are photoencapsulated within micropatterned hydrogels, their proliferation rate is a function of micropattern size. Additionally, micropattern size dictates the extent of osteogenic and chondrogenic differentiation of photoencapsulated hASC. The size of 3D micropatterned physical properties in this new hydrogel system introduces a new design parameter for regulating various cellular behaviors, and this dual‐crosslinked hydrogel system provides a new platform for studying proliferation and differentiation of stem cells in a spatially controlled manner for tissue engineering and regenerative medicine applications.     

A statistical model for the estimation of natural gas consumption

In this paper we present a statistical approach to natural gas consumption estimation of individual residential and small commercial customers. The approach is based on nonlinear regression principles. Parameters are estimated using mainly two real data sets – ordinary (approximately annual) meter readings of almost all customers and additional (approximately monthly) meter readings designed and operated within the frame of cooperation between the Institute of Computer Science of the Czech Academy of Sciences (ICS) and the West Bohemian Gas Distribution Company, a part of the RWE Group (WBG). The model was tested on various data sets. It has broad applicability in many areas of gas industry.