Nanostructures increase water droplet adhesion on hierarchically rough superhydrophobic surfaces

Hierarchical roughness is known to effectively reduce the liquid-solid contact area and water droplet adhesion on superhydrophobic surfaces, which can be seen for example in the combination of submicrometer and micrometer scale structures on the lotus leaf. The submicrometer scale fine structures, which are often referred to as nanostructures in the literature, have an important role in the phenomenon of superhydrophobicity and low water droplet adhesion. Although the fine structures are generally termed as nanostructures, their actual dimensions are often at the submicrometer scale of hundreds of nanometers. Here we demonstrate that small nanometric structures can have very different effect on surface wetting compared to the large submicrometer scale structures. Hierarchically rough superhydrophobic TiO(2) nanoparticle surfaces generated by the liquid flame spray (LFS) on board and paper substrates revealed that the nanoscale surface structures have the opposite effect on the droplet adhesion compared to the larger submicrometer and micrometer scale structures. Variation in the hierarchical structure of the nanoparticle surfaces contributed to varying droplet adhesion between the high- and low-adhesive superhydrophobic states. Nanoscale structures did not contribute to superhydrophobicity, and there was no evidence of the formation of the liquid-solid-air composite interface around the nanostructures. Therefore, larger submicrometer and micrometer scale structures were needed to decrease the liquid-solid contact area and to cause the superhydrophobicity. Our study suggests that a drastic wetting transition occurs on superhydrophobic surfaces at the nanometre scale; i.e., the transition between the Cassie-Baxter and Wenzel wetting states will occur as the liquid-solid-air composite interface collapses around nanoscale structures. Consequently, water adheres tightly to the surface by penetrating into the nanostructure. The droplet adhesion mechanism presented in this paper gives valuable insight into a phenomenon of simultaneous superhydrophobicity and high water droplet adhesion and contributes to a more detailed comprehension of superhydrophobicity overall.     

Structural Characteristics of Graphane‐Type C and BN Nanostructures by Periodic Local MP2 Approach

The structural characteristics of fully‐hydrogenated carbon and boron nitride mono‐ and multilayer slabs, together with nanotubes derived from the slabs, are investigated mainly by means of periodic local second‐order Møller–Plesset perturbation (LMP2) calculations and the results are compared with Hartree–Fock (HF), density functional theory (DFT), and dispersion function‐augmented DFT (DFT‐D) obtained ones. The investigated systems are structurally analogous to (111) and (110) slabs of diamond, where the hydrogenated (111) slab of diamond corresponds to the experimentally known graphane. Multilayering of monolayers and nanotubes is energetically favorable at the LMP2 level for both C and BN, while HF and DFT are not able to reproduce this behavior for CH systems. The work highlights the importance of utilizing methods capable of properly describing weak interactions in the investigation of dispersively‐bound systems such as the multilayered graphanes and the corresponding nanotubes.     

Disposable roll-to-roll hot embossed electrophoresis chip for detection of antibiotic resistance gene mecA in bacteria

We present a high-throughput roll-to-roll (R2R) manufacturing process for foil-based polymethyl methacrylate (PMMA) chips of excellent optical quality. These disposable, R2R hot embossed microfluidic chips are used for the identification of the antibiotic resistance gene mecA in Staphylococcus epidermidis. R2R hot embossing is an emerging manufacturing technology for polymer microfluidic devices. It is based on continuous feeding of a thermoplastic foil through a pressurized area between a heated embossing cylinder and a blank counter cylinder. Although mass fabrication of foil-based microfluidic chips and their use for biological applications were foreseen already some years ago, no such studies have been published previously.     

Homoleptic pnictogen-chalcogen coordination complexes

The synthesis and structural characterization of dicationic selenium and tellurium analogues of the carbodiphosphorane and triphosphenium families of compounds are reported. These complexes, [Ch(dppe)][OTf](2) [Ch = Se, Te; dppe = 1,2-bis(diphenylphosphino)ethane; OTf = trifluoromethanesulfonate], are formed using [Ch](2+) reagents via a ligand-exchange protocol and represent extremely rare examples of homoleptic pnictogen → chalcogen coordination complexes. The corresponding arsenic compounds were also prepared, [Ch(dpAse)][OTf](2) [Ch = Se, Te; dpAse = 1,2-bis(diphenylarsino)ethane], exhibiting the first instance of an arsenic → chalcogen dative bond. The electronic structures of these unique compounds were determined and compared to previously reported chalcogen dications.     

Fourier Transform Infrared Spectroscopy of Aliphatic bis(Amidinohydrazones) and Their Deuterated Analogues

The first study on the infrared spectroscopy of the bis(amidinohydrazones) of various glyoxals is reported. The compounds studied include the antileukemic agents glyoxal bis(amidinohydrazone) and methylglyoxal bis(amidinohydrazone) (Mitoguazone) as well as seven mono-and dialkylglyoxal analogues thereof. Free bases as well as doubly protonated species (divalent salts) were investigated. Selectively deuterated analogues were also studied and were synthesized by exchanging nitrogen-bound hydrogen atoms for deuterium atoms. The effects of substituents, protonation and deuteration on the FT-IR spectra of the compounds are discussed.     

MRI rotating frame relaxation measurements for articular cartilage assessment

In the present work we introduced two MRI rotating frame relaxation methods, namely adiabatic T_1ρ and Relaxation Along a Fictitious Field (RAFF), along with an inversion-prepared Magnetization Transfer (MT) protocol for assessment of articular cartilage. Given the inherent sensitivity of rotating frame relaxation methods to slow molecular motions that are relevant in cartilage, we hypothesized that adiabatic T_1ρ and RAFF would have higher sensitivity to articular cartilage degradation as compared to laboratory frame T₂ and MT. To test this hypothesis, a proteoglycan depletion model was used. Relaxation time measurements were performed at 0 and 48 h in 10 bovine patellar specimens, 5 of which were treated with trypsin and 5 untreated controls were stored under identical conditions in isotonic saline for 48 h. Relaxation times measured at 48 h were longer than those measured at 0 h in both groups. The changes in T₂ and MT relaxation times after 48 h were approximately 3 times larger in the trypsin treated specimens as compared to the untreated group, whereas increases of adiabatic T_1ρ and RAFF were 4 to 5 fold larger. Overall, these findings demonstrate a higher sensitivity of adiabatic T_1ρ and RAFF to the trypsin-induced changes in bovine patellar cartilage as compared to the commonly used T₂ and MT. Since adiabatic T_1ρ and RAFF are advantageous for human applications as compared to standard continuous-wave T_1ρ methods, adiabatic T_1ρ and RAFF are promising tools for assessing cartilage degradation in clinical settings.     

Nonlinear parabolic capacity and polar sets of superparabolic functions

We extend the theory of the thermal capacity for the heat equation to nonlinear parabolic equations of the $p$ -Laplacian type. We study definitions and properties of the nonlinear parabolic capacity and show that the capacity of a compact set can be represented via a capacitary potential. As an application, we show that polar sets of superparabolic functions are of zero capacity. The main technical tools used include estimates for equations with measure data and obstacle problems.     

Palladium-catalyzed dehydrogenative β'-functionalization of β-keto esters with indoles at room temperature

The dehydrogenative β'-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β'-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented.     

Heavy quarkonium in vector and scalar channels

We study quarkonium in hot QCD, emphasizing its nature as a short-lived transient with an exponentially decaying wave function. The heavy quark mass allows for a nonrelativistic expansion around the two-quark threshold, and the static potential is then seen to contain a temperature-dependent imaginary part, which leads to an unstable quark-antiquark state. We solve the corresponding Schrödinger equation and estimate the spectral functions in different channels. In particular, through careful evaluation we find a peak also in the scalar channel, although it is strongly suppressed with respect to the vector channel peak. We also plot the dilepton production rate, which shows a peak-like structure even at temperatures so high that the peak in the spectral function has disappeared.     

Carleman estimates and inverse problems for Dirac operators

We consider limiting Carleman weights for Dirac operators and prove corresponding Carleman estimates. In particular, we show that limiting Carleman weights for the Laplacian also serve as limiting weights for Dirac operators. As an application we consider the inverse problem of recovering a Lipschitz continuous magnetic field and electric potential from boundary measurements for the Pauli Dirac operator. M. Salo is supported by the Academy of Finland. L. Tzou is supported by the Doctoral Post-Graduate Scholarship from the Natural Science and Engineering Research Council of Canada. This article was written while L. Tzou was visiting the University of Helsinki and TKK, whose hospitality is gratefully acknowledged. The authors would like to thank András Vasy and Lauri Ylinen for useful comments.