Novel adhesive system based on 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) and hyperbranched polyglycerols

Two hyperbranched polyglycerols bearing 1,1,1-tris(hydroxymethyl)propane or Bisphenol A core and terminal hydroxyl functionality were examined as components of novel wood adhesive systems. Two 1,3-dimethylol-4,5-dihydroxyethyleneurea resins (DMDHEU) were used as crosslinkers. Shear strength tests revealed that the adhesives containing up to 75 wt% of renewable glycerol-derived polyglycerols retained performance comparable to that of neat DMDHEU. The results give way to extending the area of application of hyperbranched polyglycerols in the field of wood adhesives.     

Strategies to obtain pattern fidelity in nanowire growth from large-area surfaces patterned using nanoimprint lithography

Position controlled nanowire growth is important for nanowire-based optoelectronic components which rely on light emission or light absorption. For solar energy harvesting applications, dense arrays of nanowires are needed; however, a major obstacle to obtaining dense nanowire arrays is seed particle displacement and coalescing during the annealing stage prior to nanowire growth. Here, we explore three different strategies to improve pattern preservation of large-area catalyst particle arrays defined by nanoimprint lithography for nanowire growth. First, we see that heat treating the growth substrate prior to nanoimprint lithography improves pattern preservation. Second, we explore the possibility of improving pattern preservation by fixing the seed particles in place prior to annealing by modifying the growth procedure. And third, we show that a SiN _x growth mask can fully prevent seed particle displacement. We show how these strategies allow us to greatly improve the pattern fidelity of grown InP nanowire arrays with dimensions suitable for solar cell applications, ultimately achieving 100% pattern preservation over the sampled area. The generic nature of these strategies is supported through the synthesis of GaAs and GaP nanowires.

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Terahertz time domain spectroscopy of graphene and MXene polymer composites

The rising demand for faster and more efficient electronic devices forces electronics industry to shift toward terahertz frequencies. Therefore there is a growing need for efficient, lightweight, and easy to produce absorbing materials in the terahertz range for electromagnetic interference (EMI) shielding and related applications. This study presents a study on basic optical properties of two types polymer-based composites loaded with two-dimensional structures—graphene and MXene phases (Ti₂C). In said range, total EMI shielding efficiency (SE) and its components, the absorption coefficient (α ), refractive index, and complex dielectric function are investigated. The ratio of SE absorption component to reflection component (SE_ABS :SE_R ) of fabricated composites is equal or higher than 30:1 in over 80% of studied range. The fabricated composites exhibit low (<0.1) loss tangent in studied range. The addition of 1 wt% of graphene increases the composite α over 10-fold in respect to pure polymer–up to 60 cm⁻¹ for frequency higher than 2 THz.     

Time dependence of bioactive compounds and antioxidant capacity during germination of different cultivars of broccoli and radish seeds

Optimisation of the germination process of different cultivars of broccoli (Brassica oleracea var. italica cv. Lucky, cv. Tiburon and cv. Belstar) and radish (Raphanus sativus cv. Rebel and cv. Bolide) seeds in relation to the content of glucosinolates (GLS), vitamin C and total antioxidant capacity was carried out in order to maximise the health-promoting properties of Brassica sprouts. The content of total and individual GLS varied between species, among cultivars, and germination time. Glucoraphanin in broccoli and glucoraphenin in radish were the predominant GLS in raw seeds (61–77 and 63–129 μmol/g DM, respectively) and, although their content decreased during germination, they were maintained in rather large proportions in sprouts. Vitamin C was not detected in raw seeds and its content increased sharply in broccoli and radish sprouts (162–350 and 84–113 mg/100 g DM, respectively). Raw brassica seeds are an excellent source of antioxidant capacity (64–90 and 103–162 μmol Trolox/g DM in broccoli and radish, respectively) and germination led to a sharp increase. Germination of broccoli cv. Belstar and radish cv. Rebel for 4 days provided the largest glucoraphanin and glucoraphenin content, respectively, and also brought about large amounts of vitamin C and antioxidant capacity.     

Modification of physicochemical properties of actin filaments suppresses cell fragmentation in the execution phase of staurosporine-induced apoptotic processes

Effects of jasplakinolide (JSP), a stabilizer of F-actin, and latrunculin A (LTA), a destabilizer of F-actin, on a series of events occurring in the execution phase of staurosporine (STS)-induced apoptotic processes were studied using human osteosarcoma 143B cells. Time-dependent apparent increases of the population of cells with collapsed membrane potential of mitochondria (Delta Psi(m)) caused by STS treatment were not due to actual decreases in the Delta Psi(m) per cell, but due to the fragmentation of cells resulting in decreases in the number of active mitochondria per cell. Decreases in the Delta Psi(m) in fragmented cells occurred late in the execution phase. Both JSP and LAT failed to prevent STS-induced release of cytochrome c from mitochondria followed by the activation of caspases 3 and 9, the cleavage of poly (ADP-ribose) polymerase (PARP) and apoptotic nuclear fragmentation. However, both drugs prevented STS-induced apoptotic cell fragmentation and decreases in the Delta Psi(m). These results indicate that physicochemical states of actin filaments play a certain role in the execution phase of STS-induced apoptotic processes.     

Optimization of subtractive-transformative hybrid processes supported by the technological heredity concept

This paper presents the optimization procedure of a hybrid removal-forming type process based on the minimum energy consumption and demanded surface roughness which is supported by the analysis of transformation of the surface and sublayer properties termed as the technological heredity. The experimental investigation covers an alloy steel hardened to 35 HRC and 55 HRC which was initially turned using coated carbide and CBN tools and subsequently burnished to produce surfaces with Ra roughness parameter of about 0.15 μm. The modifications of the initial surface profiles, microstructure and microhardness of the sublayer were determined and relevant technological limits are selected.     

A Photoexcited Porphyrin System as a Biomimetic Catalyst for D-limonene Biotransformation

A photoexcited porphyrin system has been found to be an efficient catalyst for D-limonene biotransformation. The catalyst showed high selectivity in hydroxylation of D-limonene. The best catalyst for limonene biotransformation was 5,10,15,20-Tetraphenylporphyrin (H₂TPP), which gave the highest accumulation of carvone and an unknown product with a verbenone-like mass spectrum. The highest conversion yield of these products was favoured at 1:2 molar ratio of H₂TPP to limonene. Some factors affecting the biotransformation yield were also investigated. Maximal yield of carvone was obtained in the medium containing 90% of the substrate, within the period of 18–36 h. Mechanism involved in limonene biotransformation catalysed by H₂TPP is also discussed.     

Comparison of approaches to the numerical modelling of pure metals solidification using the control volume method

The thermal processes proceeding in the casting-mould system are analysed. Solidification process can be described in the different ways. One of them consists in the application of the Fourier–Kirchhoff equation in which the source function controlling the phase change is introduced. In this paper, two approaches to the modelling of pure metals solidification, i.e. the solidification proceeding at the constant temperature and in the artificially introduced interval of temperature are considered. Numerical model used at the stage of computations is constructed using the Control Volume Method in which the principle of conservation of energy (taking also into account the release of latent heat of solidification) is applied to each control volume ensuring the correctness of the model. The use of Voronoi/Thiessen tessellation to the discretization of the casting-mould system can accurately reproduce the shape of each sub-domain. In the final part of the paper, the examples of computations are shown.     

Influence of aluminium electrode preparation on PCE values of polymeric solar cells based on P3HT and PCBM

The main goal of the paper was investigation of influence of aluminum electrode preparation via thermal evaporation (TE) and the magnetron sputtering (MS) on power conversion efficiency (PCE) of polymeric solar cells. The photovoltaic properties of such three kinds devices based on poly(3-hexylthiophene-2,5-diyl) (P3HT) as ITO/P3HT/Al, ITO/P3HT:PCBM (1:1, w/w)/Al and ITO/PEDOT:PSS/P3HT:PCBM (1:1, w/w)/Al were investigated. For the constructed devices impedance spectroscopy were analyzed. For devices lack of PEDOT:PSS layer or lack of PCBM, photovoltaic parameters were very low and similar to the parameters obtained for device with Al electrode prepared by magnetron sputtering. The devices comprising PEDOT:PSS with P3HT:PCBM showed the best photovoltaic parameters such as a V_OC of 0.60 V, J_SC of 4.61 mA/cm², FF of 0.21, and PCE of 5.7 × 10^?1%.     

Correlating the effects of ash elements and their association in the fuel matrix with the ash release during pulverized fuel combustion

During pulverized fuel combustion, inorganic elements such as alkalis, sulfur, chlorine, calcium and magnesium, as well as a range of minor elements are partly released into the gas phase. These gas-borne species can nucleate, coagulate and condense to form either aerosol particles or sticky layers on ash particles, leading to ash deposition and corrosion problems in power utilities. Furthermore, the fine aerosols can lead to harmful gaseous and particulate emissions. It is well documented that the mode of occurrence and the chemical speciation of ash forming elements in the coal/biomass structure are important for the release behavior of mineral components. In the presented work, this is investigated by performing quantitative elemental investigations of ash releases for two different coals (a Polish and a UK coal) and six diverse biomass fuels (Wood bark, Wood chips, Waste wood, Olive residue, Saw dust and Straw). The tests are performed within the Lab-scale Combustion Simulator (LCS) of the Energy Research Centre of the Netherlands (ECN). The operating conditions applied were that of a typical pulverized fuel (PF) fired boiler i.e. atmospheric pressure, high temperatures of 1400-1650 °C, and high heating rate of 10⁵ K/s. Gas phase elemental release of alkalis, sulfur, chlorine, calcium and magnesium has been quantified at relevant high carbon conversion levels. With the performed set of experiments several of the past observations from the literature are reconfirmed. In addition to this, based on the extensive data pool at hand, a simple but reliable (R² > 0.95) set of linear correlations have been proposed to predict the elemental release of potassium, sodium, chlorine and sulfur. It is also concluded that such linear expressions can be particularly effective for the prediction of elemental release from the fuels of similar characteristics, such as woody biomass.