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Pitcher plants of the genus Nepenthes have highly specialized leaves adapted to attract, capture, retain, and digest arthropod prey. Several mechanisms have been proposed for the capture of insects, ranging from slippery epicuticular wax crystals to downward-pointing lunate cells and alkaloid secretions that anesthetize insects. Here we report that perhaps the most important capture mechanism has thus far remained overlooked. It is based on special surface properties of the pitcher rim (peristome) and insect \"aquaplaning.\" The peristome is characterized by a regular microstructure with radial ridges of smooth overlapping epidermal cells, which form a series of steps toward the pitcher inside. This surface is completely wettable by nectar secreted at the inner margin of the peristome and by rain water, so that homogenous liquid films cover the surface under humid weather conditions. Only when wet, the peristome surface is slippery for insects, so that most ant visitors become trapped. By measuring friction forces of weaver ants (Oecophylla smaragdina) on the peristome surface of Nepenthes bicalcarata, we demonstrate that the two factors preventing insect attachment to the peristome, i.e., water lubrication and anisotropic surface topography, are effective against different attachment structures of the insect tarsus. Peristome water films disrupt attachment only for the soft adhesive pads but not for the claws, whereas surface topography leads to anisotropic friction only for the claws but not for the adhesive pads. Experiments on Nepenthes alata show that the trapping mechanism of the peristome is also essential in Nepenthes species with waxy inner pitcher walls.

Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive. Here we present the crystal structure of a complex of a cytidine deaminase with ssDNA bound in the active site at 2.2 Å. This structure not only visualizes the active site poised for catalysis of APOBEC3A, but pinpoints the residues that confer specificity towards CC/TC motifs. The APOBEC3A–ssDNA complex defines the 5′–3′ directionality and subtle conformational changes that clench the ssDNA within the binding groove, revealing the architecture and mechanism of ssDNA recognition that is likely conserved among all polynucleotide deaminases, thereby opening the door for the design of mechanistic-based therapeutics. Cytidine deaminases are evolutionarily conserved enzymes that edit genomes by deaminating cytidine to uridine. Here the authors present the crystal structure of APOBEC3A with a single-stranded DNA substrate bound in the active site to shed light on the mechanism and specificity of substrate recognition.

We report on the nature of the interlayer magnetic interactions in NiFe/Cu/Co films. By probing the quasi-static and dynamic magnetic properties of biphase ferromagnetic films, with soft and hard ferromagnetic phases intermediated by a non-magnetic layer, we address aspects of the coupling between magnetic layers. Our results demonstrate the nature of the interlayer magnetic coupling in biphase films. We also disclose the asymmetric magnetoimpedance effect as a fingerprint of the nature of the magnetic interlayer interactions playing key role in the magnetization dynamics of the system. We revisit in literature data and ideas on the asymmetric magnetoimpedance and the nature of the magnetic interactions in biphase ferromagnetic systems. Then, we compare our findings with results for biphase ribbons and microwires. Our observations raise the fundamental similarities and differences in the asymmetric magnetoimpedance of these structures.

We investigate the magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process through the calorimetric method. Specifically, we propose a theoretical approach to magnetic hyperthermia from a thermodynamic point of view. To test the robustness of the approach, we perform hyperthermia experiments and analyse the thermal behavior of magnetite and magnesium ferrite magnetic nanoparticles dispersed in water submitted to an alternating magnetic field. From our findings, besides estimating the specific loss power value from a non-adiabatic and radiating process, thus enhancing the accuracy in the determination of this quantity, we provide physical meaning to a parameter found in literature that still remained not fully understood, the effective thermal conductance, and bring to light how it can be obtained from experiment. In addition, we show our approach brings a correction to the estimated experimental results for specific loss power and effective thermal conductance, thus demonstrating the importance of the heat loss rate due to the thermal radiation in magnetic hyperthermia.

The leaves of Nepenthes pitcher plants are specialized pitfall traps which capture and digest arthropod prey. In many species, insects become trapped by 'aquaplaning' on the wet pitcher rim (peristome). Here we investigate the ecological implications of this capture mechanism in Nepenthes rafflesiana var. typica. We combine meteorological data and continuous field measurements of peristome wetness using electrical conductance with experimental assessments of the pitchers' capture efficiency. Our results demonstrate that pitchers can be highly effective traps with capture rates as high as 80% but completely ineffective at other times. These dramatic changes are due to the wetting condition of the peristome. Variation of peristome wetness and capture efficiency was perfectly synchronous, and caused by rain, condensation and nectar secreted from peristome nectaries. The presence of nectar on the peristome increased surface wetness mainly indirectly by its hygroscopic properties. Experiments confirmed that pitchers with removed peristome nectaries remained generally drier and captured prey less efficiently than untreated controls. This role of nectar in prey capture represents a novel function of plant nectar. We propose that the intermittent and unpredictable activation of Nepenthes pitcher traps facilitates ant recruitment and constitutes a strategy to maximize prey capture.

In this work, a nanohybrid material was developed and used for the first time to the kinetic resolution of secondary alcohols as rac -indanol, rac -1-phenylethanol ( rac -1), rac -1-(3-bromophenyl)-1-ethanol ( rac -2) and rac -1-(3-methylphenyl)-1-ethanol ( rac -3). Chiral indanol is used as a precursor intermediate for the synthesis of enantiomeric drugs, such as (+)-Indatraline, Irindalone, Indinavir, (+)-Sertraline and Rasagiline mesylate. Chiral 1-phenylethanol is used as an ophthalmic preservative, a solvatochromic dye and an inhibitor of cholesterol absorption and as a mild floral fragrance. For this purpose, the ultrasound irradiation was used to couple APTES on the superparamagnetic nanoparticles surface. Then, the system was activated with glutaraldehyde and used as a support for immobilization of lipase from Pseudomonas fluorescens. Thermal stability analysis was performed in buffer and hexane, showing an excellent stability in buffer solution at 60 °C, holding 72% of the initial activity, even after 7 h. In hexane (40 °C), the immobilized enzyme retained 100% of activity with 693 min of half-life time at 50 °C. The high thermal stability is mainly related to the covalent bonding between enzymes and support. Immobilized lipase on magnetic support proved to be a robust biocatalyst in the kinetic resolution, leading to ( S )-indanol with high selectivity ( e.e . > 99%, E  > 200) in 1.75 h at 50 °C, being reused five times without significant loss of the activity and selectivity. The kinetic resolution of rac -1, via acetylation reaction, catalyzed by lipase from Pseudomonas fluorescens immobilized on magnetic support, led to ( R )-acetate with enantiomeric excess > 99% and to the remaining ( S )-alcohol with enantiomeric excess of 94%, conversion of 49% and E  > 200, after 48 h of reaction at 40 °C. Under the same reactions conditions, ra c-2 and rac -3 were slightly less reactive, since the corresponding ( R )-acetates were obtained with conversion values of 44%, but with high enantioselectivity (enantiomeric excesses > 99% and E values > 200). These results correspond to an important step in heterogeneous catalysis due to the ability to obtain important precursors for the synthesis of enantiomerically pure chiral drugs and other bioactive substances.

The immunoproteasome (iP) has been proposed to perform specialized roles in MHC class I antigen presentation, cytokine modulation, and T cell differentiation and has emerged as a promising therapeutic target for autoimmune disorders and cancer. However, divergence in function between the iP and the constitutive proteasome (cP) has been unclear. A global peptide library-based screening strategy revealed that the proteasomes have overlapping but distinct substrate specificities. Differing iP specificity alters the quantity of production of certain MHC I epitopes but does not appear to be preferentially suited for antigen presentation. Furthermore, iP specificity was found to have likely arisen through genetic drift from the ancestral cP. Specificity differences were exploited to develop isoform-selective substrates. Cellular profiling using these substrates revealed that divergence in regulation of the iP balances its relative contribution to proteasome capacity in immune cells, resulting in selective recovery from inhibition. These findings have implications for iP-targeted therapeutic development.

The magnetization dynamics in ZnO:Ag/NiFe heterostructures has been investigated through magnetoimpedance measurements. By annealing the ZnO:Ag layer during the production process of the samples, structural and magnetic features of the whole heterostructure are modified, showing that the dynamical magnetic response of the heterostructure is strongly dependent on the annealing temperature. The magnetoimpedance results are discussed in terms of the different mechanisms governing the magnetization dynamics at distinct frequency ranges and in terms of the evolution of the ZnO:Ag layer with annealing. The presented results open new roads for technological application of semiconductor/ferromagnetic heterostructures.

The aim of the research was to evaluate the effects of sulfonitric and CS (CS) treatment in multilayer carbon nanotubes (MWCNT) on their electrochemical and magnetic properties. Thermogravimetric analysis (TG) showed an increase in thermal properties for CS functionalized MWCNT when compared in sulfonitric medium. High resolution transmission electron microscopy (HRTEM) images revealed a reduction in the average diameter of functionalized MWCNT in the presence of CS in addition to decreasing their interlayer spaces. As evidenced by X-ray Diffraction (XRD) patterns. In addition, X-ray photoelectron spectroscopy (XPS) spectra proved the functional groups inclusion of CS and sulfonitric solution on the (carbon nanotubes) CNT matrix. Unlike pristine MWCNT solutions which are unstable in aqueous media, functionalization with acidic solutions and contributed to its potential stabilization. The results obtained by Raman Spectroscopy prove the functionalization through the insertion of functional groups in the walls of the nanotubes. The electroanalysis showed higher capacitance values by mass and by area for samples functionalized with acids and that the addition of CS during functionalization increases the resistance to current flow, causing an insulating effect.

We investigate the structural, morphological, chemical, and magnetic properties of Ni–NiO nanocomposites synthesized through two distinct routes, sol–gel and coprecipitation, followed by calcination. By considering several techniques we show that the resulting nanocomposites, as well as their properties, are strongly dependent on both, synthesis method and calcination temperature. Hence, we explore the possibility of tailoring the physical properties of the nanocomposite by modifying production parameters. The results place the employed routes as a simple, low-cost candidate to the production of Ni–NiO nanocomposites, especially nickel oxide. Nanoparticles of Nio/Ni produced by sol-gel route. Highlights Sol-gel and co-precipitaion routes to produce Ni-NiO and NiO nanopowders. Structural, morphological and magnetic properties of Ni-NiO and NiO nanopowders. Tailoring nanocomposites' properties via synthesis and calcination temperature.