The conduction pathway of potassium channels is water free under physiological conditions.

Ion conduction through potassium channels is a fundamental process of life. On the basis of crystallographic data, it was originally proposed that potassium ions and water molecules are transported through the selectivity filter in an alternating arrangement, suggesting a "water-mediated" knock-on mechanism. Later on, this view was challenged by results from molecular dynamics simulations that revealed a "direct" knock-on mechanism where ions are in direct contact. Using solid-state nuclear magnetic resonance techniques tailored to characterize the interaction between water molecules and the ion channel, we show here that the selectivity filter of a potassium channel is free of water under physiological conditions. Our results are fully consistent with the direct knock-on mechanism of ion conduction but contradict the previously proposed water-mediated knock-on mechanism

The importance of genetic parenthood for infertile men and women

STUDY QUESTION: Do men and women beginning to attend a fertility clinic prefer genetic over non-genetic parenthood? SUMMARY ANSWER: Nearly, all infertile men and women prefer genetic parenthood. WHAT IS KNOWN ALREADY: Clinicians assume that all infertile couples prefer genetic parenthood over non-genetic parenthood and, therefore, consider treatments with donor gametes an option of last resort. Previous studies of the desire for parenthood identified 30 motivations for genetic parenthood, and 51 motivations for which having a genetically related child is not strictly necessary but might be deemed required. The exact strength of the preference of infertile men and women for genetic parenthood remains unclear, as does the importance of the various motivations. STUDY DESIGN, SIZE, DURATION: A questionnaire was developed based on a literature review. It was assessed by professionals and pilot tested among patients. The coded paper-pencil questionnaire was disseminated among both partners of 201 heterosexual infertile couples after their first consultation at one of two Belgian fertility clinics between October 2015 and May 2016. PARTICIPANTS/MATERIALS, SETTING, METHODS: The survey addressed: (i) the preference for genetic parenthood for themselves and for their partner, (ii) the importance of 30 motivations for genetic parenthood and (iii) the importance of 51 other motivations for parenthood and whether these motivations require being the genetic parent of their child to be fulfilled. To simplify presentation of the results, all 81 motivations were grouped into reliable categories of motivations using psychometric analyses. MAIN RESULTS AND THE ROLE OF CHANCE: The survey was completed by 104 women and 91 men (response rate: 49%). Almost all respondents (98%) favored genetic over non-genetic parenthood for both their partner and themselves. One-third of the respondents stated they only wanted to parent their own genetically related child. Achieving genetic parenthood for their partner was considered significantly more important than achieving genetic parenthood for themselves. Within couples, men had a stronger preference for genetic parenthood (P = 0.004), but this was not significant after correction for educational level, which was significantly associated with the preference of both men and women. The 30 motivations for becoming a genetic parent clustered into 11 categories of which 'to experience a natural process' was deemed most important. The 51 motivations for becoming a parent for which having a genetically related child is not strictly necessary clustered into 14 categories of which 'to contribute to a child's well-being' and 'to experience the love of a child' were most important. Respondents deemed they would need to be the genetic parent of their child to fulfill nearly all their motivations for parenthood. LIMITATIONS REASONS FOR CAUTION: We included couples that visited the fertility clinic for the first time, and the preference for genetic parenthood might change throughout a fertility treatment trajectory. Moreover, what prospective parents expect to be important for their future well-being might not really define parents' well-being. WIDER IMPLICATIONS OF THE FINDINGS: The presumed preference of couples for genetic parenthood was confirmed. Resistance against using donor gametes is more likely among lower educated individuals. Researching whether non-genetic parents actually feel they cannot fulfill the 51 motivations for parenthood, could be a basis for developing patient informatio

Conductivity enhancement of binder-based graphene inks by photonic annealing and subsequent compression rolling

This paper describes a combination of photonic annealing and compression rolling to improve the conductive properties of printed binder-based graphene inks. High-density light pulses result in temperatures up to 500°C that along with a decrease of resistivity lead to layer expansion. The structural integrity of the printed layers is restored using compression rolling resulting in smooth, dense, and highly conductive graphene films. The layers exhibit a sheet resistance of less than 1.4Ω□-1 normalized to 25μm thickness. The proposed approach can potentially be used in a roll-to-roll manner with common substrates, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and paper, paving thereby the road toward high-volume graphene-printed electronics.</p

Structural plasticity of the selectivity filter in a nonselective ion channel

The sodium potassium ion channel (NaK) is a nonselective ion channel that conducts both sodium and potassium across the cellular membrane. A new crystallographic structure of NaK reveals conformational differences in the residues that make up the selectivity filter between the four subunits that form the ion channel and the inner helix of the ion channel. The crystallographic structure also identifies a side-entry, ion-conduction pathway for Na+ permeation that is unique to NaK. NMR studies and molecular dynamics simulations confirmed the dynamical nature of the top part of the selectivity filter and the inner helix in NaK as also observed in the crystal structure. Taken together, these results indicate that the structural plasticity of the selectivity filter combined with the dynamics of the inner helix of NaK are vital for the efficient conduction of different ions through the non-selective ion channel of NaK

Model-based Aeroservoelastic Design and Load Alleviation of Large Wind Turbine Blades

This paper presents an aeroservoelastic modeling approach for dynamic load alleviation in large wind turbines with trailing-edge aerodynamic surfaces. The tower, potentially on a moving base, and the rotating blades are modeled using geometrically non-linear composite beams, which are linearized around reference conditions with arbitrarily-large structural displacements. Time-domain aerodynamics are given by a linearized 3-D unsteady vortexlattice method and the resulting dynamic aeroelastic model is written in a state-space formulation suitable for model reductions and control synthesis. A linear model of a single blade is used to design a Linear-Quadratic-Gaussian regulator on its root-bending moments, which is finally shown to provide load reductions of about 20% in closed-loop on the full wind turbine non-linear aeroelastic model

The mucosal adjuvant cholera toxin B instructs non-mucosal dendritic cells to promote IgA production via retinoic acid and TGF-β

It is currently unknown how mucosal adjuvants cause induction of secretory immunoglobulin A (IgA), and how T cell-dependent (TD) or -independent (TI) pathways might be involved. Mucosal dendritic cells (DCs) are the primary antigen presenting cells driving TI IgA synthesis, by producing a proliferation-inducing ligand (APRIL), B cell activating factor (BAFF), Retinoic Acid (RA), TGF-beta or nitric oxide (NO). We hypothesized that the mucosal adjuvant Cholera Toxin subunit B (CTB) could imprint non-mucosal DCs to induce IgA synthesis, and studied the mechanism of its induction. In vitro, CTB-treated bone marrow derived DCs primed for IgA production by B cells without the help of T cells, yet required co-signaling by different Toll-like receptor (TLR) ligands acting via the MyD88 pathway. CTB-DC induced IgA production was blocked in vitro or in vivo when RA receptor antagonist, TGF-beta signaling inhibitor or neutralizing anti-TGF-beta was added, demonstrating the involvement of RA and TGF-beta in promoting IgA responses. There was no major involvement for BAFF, APRIL or NO. This study highlights that synergism between CTB and MyD88-dependent TLR signals selectively imprints a TI IgA-inducing capacity in non-mucosal DCs, explaining how CTB acts as an IgA promoting adjuvant