77 research outputs found

    A narrative group model to reduce gender role conflict in adult males

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    This manuscript provides a therapeutic group model to address gender role conflict in males based on a narrative approach. The use of story telling and metaphor are central to the process because they are reflective of how men tend to communicate. This approach reflects a shift away from traditional counseling approach often seen as the antithesis of a masculine ideology. This process provides group members the opportunities to co-create and re-author socially constructed stories of masculinity and maleness that have taught males to abuse and neglect their bodies while at the same time not seek help. Unique to this model is the effort to provide empirically based outcome data on the effectiveness of the group

    Hairpins in the conformations of a confined polymer

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    If a semiflexible polymer confined to a narrow channel bends around by 180 degrees, the polymer is said to exhibit a hairpin. The equilibrium extension statistics of the confined polymer are well understood when hairpins are vanishingly rare or when they are plentiful. Here we analyze the extension statistics in the intermediate situation via experiments with DNA coated by the protein RecA, which enhances the stiffness of the DNA molecule by approximately one order of magnitude. We find that the extension distribution is highly non-Gaussian, in good agreement with Monte Carlo simulations of confined discrete wormlike chains. We develop a simple model that qualitatively explains the form of the extension distribution. The model shows that the tail of the distribution at short extensions is determined by conformations with one hairpin.Comment: Revised version. 22 pages, 7 figures, 2 tables, supplementary materia

    Visualization of defect-induced excitonic properties of the edges and grain boundaries in synthesized monolayer molybdenum disulfide

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    Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDCs) are attractive materials for next generation nanoscale optoelectronic applications. Understanding nanoscale optical behavior of the edges and grain boundaries of synthetically grown TMDCs is vital for optimizing their optoelectronic properties. Elucidating the nanoscale optical properties of 2D materials through far-field optical microscopy requires a diffraction-limited optical beam diameter sub-micron in size. Here we present our experimental work on spatial photoluminescence (PL) scanning of large size ( ≥50\geq 50 microns) monolayer MoS2_2 grown by chemical vapor deposition (CVD) using a diffraction limited blue laser beam spot (wavelength 405 nm) with a beam diameter as small as 200 nm allowing us to probe nanoscale excitonic phenomena which was not observed before. We have found several important features: (i) there exists a sub-micron width strip (∼500\sim 500 nm) along the edges that fluoresces ∼1000%\sim 1000 \% brighter than the region far inside; (ii) there is another brighter wide region consisting of parallel fluorescing lines ending at the corners of the zig-zag peripheral edges; (iii) there is a giant blue shifted A-excitonic peak, as large as ∼120\sim 120 meV, in the PL spectra from the edges. Using density functional theory calculations, we attribute this giant blue shift to the adsorption of oxygen dimers at the edges, which reduces the excitonic binding energy. Our results not only shed light on defect-induced excitonic properties, but also offer an attractive route to tailor optical properties at the TMDC edges through defect engineering.Comment: 10 pages, 4 figures in Journal of Physical Chemistry C, 201

    Photoresponse of Natural van der Waals Heterostructures

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    Van der Waals (vdW) heterostructures consisting of two dimensional materials offer a platform to obtain material by design and are very attractive owing to novel electronic states. Research on 2D van der Waals heterostructures (vdWH) has so far been focused on fabricating individually stacked atomically thin unary or binary crystals. Such systems include graphene (Gr), hexagonal boron nitride (h-BN) and member of the transition metal dichalcogenides family. Here we present our experimental study of the opto-electronic properties of a naturally occurring vdWH, known as Franckeite, which is a complex layered crystal composed of lead, tin, antimony, iron and sulfur. We present here that thin film franckeite (60 nm < d < 100 nm) behave as narrow band gap semiconductor demonstrating a wide band photoresponse. We have observed the band-edge transition at ~ 1500 nm (~830 meV) and high external quantum efficiency (EQE~3%) at room temperature. Laser power resolved and temperature resolved photocurrent measurements reveal that the photo-carrier generation and recombination are dominated by continuously distributed trap states within the band gap. To understand wavelength resolved photocurrent, we also calculated the optical absorption properties via density functional theory. Finally, we have shown that the device has fast photoresponse with rise time as fast as ~ 1 ms. Our study provides a fundamental understanding of the optoelectronic behavior in a complex naturally occurring vdWH and can open up the possibilities of producing new type of nanoscale optoelectronic devices with tailored properties.Comment: 10 pages, 5 figures (to be appeared in ACS NANO
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