Проблеми становлення і розвитку інформаційного законодавства в контексті євроінтеграції України

Щодо розвитку права і правової науки в інформаційній сфері в Україні.О развитии права и правовой науки в информационной сфере в Украине.On the development of law and law science in the informative sphere of Ukraine

Alternative nano-lithographic tools for shell-isolated nanoparticle enhanced Raman spectroscopy substrates

Chemically synthesized metal nanoparticles (MNPs) have been widely used as surface-enhanced Raman spectroscopy (SERS) substrates for monitoring catalytic reactions. In some applications, however, the SERS MNPs, besides being plasmonically active, can also be catalytically active and result in Raman signals from undesired side products. The MNPs are typically insulated with a thin (∼3 nm), in principle pin-hole-free shell to prevent this. This approach, which is known as shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), offers many advantages, such as better thermal and chemical stability of the plasmonic nanoparticle. However, having both a high enhancement factor and ensuring that the shell is pin-hole-free is challenging because there is a trade-off between the two when considering the shell thickness. So far in the literature, shell insulation has been successfully applied only to chemically synthesized MNPs. In this work, we alternatively study different combinations of chemical synthesis (bottom-up) and lithographic (top-down) routes to obtain shell-isolated plasmonic nanostructures that offer chemical sensing capabilities. The three approaches we study in this work include (1) chemically synthesized MNPs + chemical shell, (2) lithographic substrate + chemical shell, and (3) lithographic substrate + atomic layer deposition (ALD) shell. We find that ALD allows us to fabricate controllable and reproducible pin-hole-free shells. We showcase the ability to fabricate lithographic SHINER substrates which report an enhancement factor of 7.5 × 103 ± 17% for our gold nanodot substrates coated with a 2.8 nm aluminium oxide shell. Lastly, by introducing a gold etchant solution to our fabricated SHINER substrate, we verified that the shells fabricated with ALD are truly pin-hole-free.</p

In Situ Optical and X-ray Spectroscopy Reveals Evolution toward Mature CdSe Nanoplatelets by Synergetic Action of Myristate and Acetate Ligands

The growth of two-dimensional platelets of the CdX family (X = S, Se, or Te) in an organic solvent requires the presence of both long- and short-chain ligands. This results in nanoplatelets of atomically precise thickness and long-chain ligand-stabilized Cd top and bottom surfaces. The platelets show a bright and spectrally pure luminescence. Despite the enormous interest in CdX platelets for optoelectronics, the growth mechanism is not fully understood. Riedinger et al. studied the reaction without a solvent and showed the favorable role for short-chain carboxylates for growth in two dimensions. Their model, based on the total energy of island nucleation, shows favored side facet growth versus growth on the top and bottom surfaces. However, several aspects of the synthesis under realistic conditions are not yet understood: Why are both short- and long-chain ligands required to obtain platelets? Why does the synthesis result in both isotropic nanocrystals and platelets? At which stage of the reaction is there bifurcation between isotropic and 2D growth? Here, we report an in situ study of the CdSe nanoplatelet reaction under practical synthesis conditions. We show that without short-chain ligands, both isotropic and mini-nanoplatelets form in the early stage of the process. However, most remaining precursors are consumed in isotropic growth. Addition of acetate induces a dramatic shift toward nearly exclusive 2D growth of already existing mini-nanoplatelets. Hence, although myristate stabilizes mini-nanoplatelets, mature nanoplatelets only grow by a subtle interplay between myristate and acetate, the latter catalyzes fast lateral growth of the side facets of the mini-nanoplatelets

Studie naar de belasting van een trilwals op een zandpakket

In deze studie is onderzoek gedaan naar de dynamische belasting die een trilwals uitoefent op een zandpakket tijdens het verdichten van die zandpakketten. Het systeem trilwals-zandpakket is gemodelleerd tot een twee massa veer systeem. In deze studie is met name aandacht besteed aan de afleiding van de grondparameters (veerconstante, demperconstante en meetrillende grondmassa) in het model.GeotechnologyCivil Engineering and Geoscience

Micromechanics of sand grain failure and sand compaction

While there exists a considerable body of theoretical and experimental work regarding the time-independent compaction and compaction creep behaviour of sands under near-surface and upper-crustal conditions where brittle processes are important, a number of important questions remain unanswered. In particular, the brittle failure behaviour of single sand grains is poorly understood at the microphysical level, and previous experimental studies performed on sand aggregates have not systematically investigated the effect of applied stress, grain size and chemical environment on either time-independent compaction or compaction creep behaviour. In addition, theoretical models for compaction of sands by time-independent grain scale cracking lack a true micromechanistic basis and no microphysical models have been developed for compaction of sands by timedependent grain scale cracking. The present study is concerned with the development of a fundamental understanding of the micromechanical processes controlling the compaction behaviour of sands under conditions favouring brittle and elastic phenomena. The approach adopted involves theoretical and experimental investigations into the failure behaviour of single sand grains and into the compaction behaviour of sand aggregates, and addresses both time-dependent and time-independent processes. The results help provide the understanding of the fundamental processes operating during sand grain failure and sand compaction needed for on-going progress towards micromechanically based constitutive relations suitable for modelling natural and man-induced deformations of both sands and sandstones

Micromechanics of sand grain failure and sand compaction

While there exists a considerable body of theoretical and experimental work regarding the time-independent compaction and compaction creep behaviour of sands under near-surface and upper-crustal conditions where brittle processes are important, a number of important questions remain unanswered. In particular, the brittle failure behaviour of single sand grains is poorly understood at the microphysical level, and previous experimental studies performed on sand aggregates have not systematically investigated the effect of applied stress, grain size and chemical environment on either time-independent compaction or compaction creep behaviour. In addition, theoretical models for compaction of sands by time-independent grain scale cracking lack a true micromechanistic basis and no microphysical models have been developed for compaction of sands by timedependent grain scale cracking. The present study is concerned with the development of a fundamental understanding of the micromechanical processes controlling the compaction behaviour of sands under conditions favouring brittle and elastic phenomena. The approach adopted involves theoretical and experimental investigations into the failure behaviour of single sand grains and into the compaction behaviour of sand aggregates, and addresses both time-dependent and time-independent processes. The results help provide the understanding of the fundamental processes operating during sand grain failure and sand compaction needed for on-going progress towards micromechanically based constitutive relations suitable for modelling natural and man-induced deformations of both sands and sandstones