4.1 Strain-Promoted Azide–Alkyne Cycloaddition (SPAAC): Background, Substrate Preparation, and Reactivity

This chapter discusses the creative synthetic approaches to azides and cycloalkynes, provides the rationale for controlling SPAAC reactivity through tuning cycloalkyne and azide backbone modifications, and highlights research on nitrone cycloadditions with cycloalkynes. This synthetic and knowledge toolset will help in the design of better cycloalkynes and their partners to answer challenging research questions and aid the development of new applications.

Saturação por bases e doses de fósforo na produção de mudas de ipê rosa (Handroanthus impetiginosa)

O ipê rosa (Handroanthus impetiginosa) é uma espécie arbórea nativa do Brasil usada na ornamentação e recomposição florestal. Para garantir que mudas de qualidade sejam utilizadas em qualquer finalidade, para a qual se emprega essa espécie, deve-se conhecer mais a respeito das suas exigências nutricionais. Diante disso, um experimento foi realizado com o objetivo de avaliar a saturação por bases e diferentes níveis de fósforo (P) na produção de mudas do ipê rosa. O experimento foi conduzido em delineamento inteiramente casualizado com nove tratamentos e cinco repetições: T0 (100% substrato comercial); T1 (V50% de saturação por bases); T2 (V60% de saturação por bases); T3 (V50% de saturação por bases + 50 kg ha-1 de P2O5); T4 (V50% de saturação por bases + 100 kg ha-1 de P2O5); T5 (V50% de saturação por bases + 150 kg ha-1 de P2O5); T6 (V60% de saturação por bases + 50 kg ha-1 de P2O5); T7 (V60% de saturação por bases + 100 kg ha-1 de P2O5); T8 (V60% de saturação por bases + 150 kg ha-1 de P2O5). As características morfológicas foram avaliadas ao final de 90 dias. A saturação por bases e a adubação fosfatada não influenciaram no crescimento em altura e em diâmetro das mudas de H. impetiginosa, porém, influenciaram na produção de massa seca. Dessa forma, recomenda-se, para a produção de mudas de H. impetiginosa, a preparação do substrato sendo: solo com V60% de saturação por bases + 150 kg ha-1 de P2O5. Palavras-chave: Ipê rosa, calagem, fosfatagem, nutrição de plantas, viveiro. Abstract The pink ipe (Handroanthus impetiginosa) is a tree species native to Brazil that is used in forest ornamentation and restoration. To ensure that quality seedlings are used for any purpose, for which this species is used, it is necessary to know more about nutritional requirements. Therefore, an experiment was developed to evaluate base saturation and different phosphorus (P) levels in the pink ipe seedlings production. The experiment was carried out in a completely randomized design with nine treatments and five replications: T0 (100% commercial substrate); T1 (V50% of base saturation); T2 (V60% of base saturation); T3 (V50% of base saturation + 50 kg ha-1 of P2O5) ; T4 (V50% of base saturation + 100 kg ha-1 of P2O5); T5 (V50% of base saturation + 150 kg ha-1 of P2O5); T6 (V60% of base saturation + 50 kg ha-1 of P2O5); T7 (V60% of base saturation + 100 kg ha-1 of P2O5); T8 (V60% of base saturation + 150 kg ha-1 P2O5). Morphological characteristics of the plants were evaluated after 90 days. Base saturation and phosphate fertilization did not influence H. impetiginosa seedling height and diameter growth but influenced dry mass production. Thus, for the H. impetiginosa seedlings production, substrate preparation: soil with V60% of base saturation + 150 kg ha-1 of P2O5 is recommended. Keywords: Pink ipe, liming, phosphating, plant nutrition, nursery.

Growth of GaP Layers on Si Substrates in a Standard MOVPE Reactor for Multijunction Solar Cells

Gallium phosphide (GaP) is an ideal candidate to implement a III-V nucleation layer on a silicon substrate. The optimization of this nucleation has been pursued for decades, since it can form a virtual substrate to grow monolithically III-V devices. In this work we present a GaP nucleation approach using a standard MOVPE reactor with regular precursors. This design simplifies the epitaxial growth in comparison to other routines reported, making the manufacturing process converge to an industrial scale. In short, our approach intends to mimic what is done to grow multijunction solar cells on Ge by MOVPE, namely, to develop a growth process that uses a single reactor to manufacture the complete III-V structure, at common MOVPE process temperatures, using conventional precursors. Here, we present the different steps in such GaP nucleation routine, which include the substrate preparation, the nucleation itself and the creation of a p-n junction for a Si bottom cell. The morphological and structural measurements have been made with AFM, SEM, TEM and Raman spectroscopy. These results show a promising surface for subsequent III-V growth with limited roughness and high crystallographic quality. For its part, the electrical characterization reveals that the routine has also formed a p-n junction that can serve as bottom subcell for the multijunction solar cell.

EFFECT OF SUBSTRATE PREPARATION ON THE LOAD-BEARING BEHAVIOR OF CFRP-CONFINED RC COLUMNS

The confinement of reinforced concrete (RC) columns with fiber reinforced polymer (FRP) jackets is an effective measure for the strengthening and retrofitting of existing structures. The jacket withstands the increasing lateral strains of the axially loaded column causing a three-dimensional stress state inside the concrete. In the result, a higher concrete compressive strength can be achieved. So far, extensive international research on FRP-confined concrete has been conducted, but there are still some open issues regarding the influence of different parameters on the load-bearing behavior. This paper is focusing on the effect of the substrate preparation on the maximum concrete strength and stress-strain behavior. Therefore, an experimental study of carbon fiber reinforced polymer (CFRP) confined concrete cylinders with various substrate conditions and preparation methods is presented. The results are compared with previous investigations and assessed accordingly. Furthermore, recommendations regarding the substrate preparation by current national codes and guidelines are specified and considered critically.

Demonstration of nearly pinhole-free epitaxial aluminum thin films by sputter beam epitaxy

Superconducting resonators with high quality factors have been fabricated from aluminum films, suggesting potential applications in quantum computing. Improvement of thin film crystal quality and removal of void and pinhole defects will improve quality factor and functional yield. Epitaxial aluminum films with superb crystallinity, high surface smoothness, and interface sharpness were successfully grown on the c-plane of sapphire using sputter beam epitaxy. This study assesses the effects of varying substrate preparation conditions and growth and prebake temperatures on crystallinity and smoothness. X-ray diffraction and reflectivity measurements yield extensive Laue oscillations and Kiessig thickness fringes for films grown at 200 °C under 15 mTorr Ar, indicating excellent crystallinity and surface smoothness; moreover, an additional substrate preparation procedure which involves (1) a modified substrate cleaning procedure and (2) prebake at 700 °C in 20 mTorr O2 is shown by atomic force microscopy to yield nearly pinhole-free film growth while maintaining epitaxy and high crystal quality. The modified cleaning procedure is environmentally friendly and eliminates the acid etch steps common to conventional sapphire preparation, suggesting potential industrial application both on standard epitaxial and patterned surface sapphire substrates.

Structural characterization of inkjet printed capacitor layers in various technological conditions

Purpose The purpose of this paper is to analyze the individual steps during the printing of capacitor structures. The method of substrate preparation, the obtained roughness of conductive and dielectric layers are examined. Moreover, the capacitances of the obtained capacitors were examined. Design/methodology/approach Surface roughness and microscopic analysis were used to assess the quality of printed conductive structures. Two criteria were used to assess the quality of printed dielectric structures: the necessary lack of discontinuity of layers and minimal roughness. To determine the importance of printing parameters, a draft experimental method was proposed. Findings The optimal way to clean the substrate has been determined. The most important parameters for the dielectric layer (i.e. drop-space, table temperature, curing time and temperature) were found. Research limitations/implications If dielectric layers are printed correctly, most problems with printing complex electronic structures (transistors, capacitors) will be eliminated. Practical implications The tests performed identified the most important factors for dielectric layers. Using them, capacitors of repeatable capacity were printed. Originality/value In the literature on this subject, no factors were found which were responsible for obtaining homogeneous dielectric layers.