Quantum Tunneling of Thermal Protons Through Pristine Graphene

Atomically thin two-dimensional materials such as graphene and hexagonal boron nitride have recently been found to exhibit appreciable permeability to thermal protons, making these materials emerging candidates for separation technologies [S. Hu et al., Nature 516, 227 (2014); M. Lozada-Hidalgo et al., Science 351, 68 (2016).]. These remarkable findings remain unexplained by density-functional electronic structure calculations, which instead yield barriers that exceed by 1.0 eV those found in experiments. Here we resolve this puzzle by demonstrating that the proton transfer through pristine graphene is driven by quantum nuclear effects, which substantially reduce the transport barrier by up to 1.4 eV compared to the results of classical molecular dynamics (MD). Our Feynman-Kac path-integral MD simulations unambiguously reveal the quantum tunneling mechanism of strongly interacting hydrogen ions through two-dimensional materials. In addition, we predict a strong isotope effect of 1 eV on the transport barrier for graphene in vacuum and at room temperature. These findings not only shed light on the graphene permeability to protons and deuterons, but also offer new insights for controlling the underlying quantum ion transport mechanisms in nanostructured separation membranes

Properties of wool dyed with pinecone powder as a by-product colorant

The properties of the pinecone, an Iranian natural and low cost agricultural by-product, have been studied for its potential use in textile dyeing. In this research, wool fibres due to their high affinity towards the aqueous extract of natural dyes have been used and their dyeability with powdered pinecone is studied. The effects of two different variables, including dye concentration and mordant type on the color properties of dyed wool fibres are investigated. To determine the functional group of pinecone colorant, FTIR test is also performed. The colorimetric properties (color strength, color difference, color coordinates CIE Lab) and the color fastness (wash and light) results are considered for quantifying evaluation of dye concentration and mordant type effects. The results show that the wool possesses high affinity towards pinecone dyeing solution, and the used mordant methods exhibit different shades ranging from beige to brown with good fastness

Structure and stability of molecular crystals with many body dispersion inclusive density functional tight binding

Accurate prediction of structure and stability of molecular crystals is crucial in materials science and requires reliable modeling of long-range dispersion interactions. Semi-empirical electronic structure methods are computationally more efficient than their ab initio counterparts, allowing structure sampling with significant speedups. Here, we combine the Tkatchenko-Scheffler van-der-Waals method (TS) and the many body dispersion method (MBD) with third-order density functional tight-binding (DFTB3) via a charge population-based method. We find an overall good performance for the X23 benchmark database of molecular crystals, despite an underestimation of crystal volume that can be traced to the DFTB parametrization. We achieve accurate lattice energy predictions with DFT+MBD energetics on top of vdW-inclusive DFTB3 structures, resulting in a speedup of up to 3000 times compared to a full DFT treatment. This suggests that vdW-inclusive DFTB3 can serve as a viable structural prescreening tool in crystal structure prediction

Can smartwatches replace smartphones for posture tracking?

This paper introduces a human posture tracking platform to identify the human postures of sitting, standing or lying down, based on a smartwatch. This work develops such a system as a proof-of-concept study to investigate a smartwatch's ability to be used in future remote health monitoring systems and applications. This work validates the smartwatches' ability to track the posture of users accurately in a laboratory setting while reducing the sampling rate to potentially improve battery life, the first steps in verifying that such a system would work in future clinical settings. The algorithm developed classifies the transitions between three posture states of sitting, standing and lying down, by identifying these transition movements, as well as other movements that might be mistaken for these transitions. The system is trained and developed on a Samsung Galaxy Gear smartwatch, and the algorithm was validated through a leave-one-subject-out cross-validation of 20 subjects. The system can identify the appropriate transitions at only 10 Hz with an F-score of 0.930, indicating its ability to effectively replace smart phones, if needed

Quantum tunneling of thermal protons through pristine graphene

Engineering of atomically thin membranes for hydrogen isotope separation is an actual challenge which has a broad range of applications. Recent experiments [M. Lozada-Hidalgo et al., Science 351, 68 (2016)] unambiguously demonstrate an order-of-magnitude difference in permeabilities of graphene-based membranes to protons and deuterons at ambient conditions, making such materials promising for novel separation technologies. Here we demonstrate that the permeability mechanism in such systems changes from quantum tunneling for protons to quasi-classical transport for heavier isotopes. Quantum nuclear effects exhibit large temperature and mass dependence, modifying the Arrhenius activation energy and Arrhenius prefactor for protons by more than 0.5 eV and by seven orders of magnitude correspondingly. Our findings not only shed light on the separation process for hydrogen isotope ions passing through pristine graphene but also offer new insights for controlling ion transport mechanisms in nanostructured separation membranes by manipulating the shape of the barrier and transport process conditions

Decoy Cell Viruria in Kidney Transplant Patients. Does it correlate with Renal Function?

Objective: BK virus (BKV) infection after kidney transplantation has been a topic of great interest in the recent decade. Prospective screening studies have revealed that BKVN is principally an early complication of renal transplantation occurring within the first post-transplant year in most cases. The aim of the present study was to observe the incidence of decoy cell viruria in renal transplant recipients. Furthermore, correlation of decoy cell viruria with graft function was assessed. Methods: This analytic cross-sectional study was conducted in the Transplant Center of Alzahra Hospital, Isfahan, Iran between Jun 2014 and June 2015. Clinical screening for polyomavirus infection was done by means of urine cytological evaluation for decoy cells. Urine samples were analyzed in three steps including 2-4 months after transplantation, three and six months later. Results: Thirty-three patients (22 male and 11 female) received kidney transplant from living donors. The average of patients' age was 41.9 +/- 12.83 (range: 20-63 years). Peritoneal and hemodialysis were used for 15.6% and 84.4% of recipients. The occurrence of decoy cell viruria at the time of enrollment, 3 and 6 months later was found in 18.2%, 10.7% and zero, respectively. Conclusion: As urine cytology is easy to perform and of low cost, it is a useful tool for the investigation of active polyoma virus infection. Moreover, the findings advocate that the presence of decoy cells along with high creatinine is a better indicator of the virus presence

Fabrication and characterization of polycaprolactone fumarate/gelatin-based nanocomposite incorporated with silicon and magnesium co-doped fluorapatite nanoparticles using electrospinning method

The aim of this study was to fabricate and characterize biodegradable polycaprolactone fumarate(PCLF)/gelatin-based nanocomposite incorporated with the 0, 5 and 10 wt% silicon and magnesium co-doped fluorapatite nanoparticles (Si -Mg-FA) membranes using electrospinning process for guided bone regeneration (GBR) and guided tissue regeneration (GTR) applications. Results demonstrated the formation of randomly-oriented and defect-free fibers with various fiber sizes depending on the Si -Mg-FA content. Moreover, incorporation of 5 wt% Si -Mg-FA significantly improved the mechanical strength (1.5times) compared to the mechanical strength of PCLF/gelatin membrane and nanocomposite with 10 wt% nanoparticles. There was no clear difference between degradation rate of PCLF/gelatin and PCLF/gelatin with 5 wt% nanoparticles at 7, 14 and 28 days of immersion in phosphate buffer saline while 10 wt% nanoparticles significantly increased biodegradation of PCLF/gelatin, and no cytotoxic effect of membranes was seen. Finally, scanning electron microscopy (SEM) micrographs of fibroblast cells cultured on the samples demonstrated that the cells were completely attached and spread on the surface of nanocomposites. In summary, PCLF/gelatin membranes consisting of 5 wt% Si -Mg-FA nanoparticles could provide appropriate mechanical and biological properties and fairly good degradation rate, making it appropriate for GTR/GBR applications