Tuning metal/superconductor to insulator/superconductor coupling via control of proximity enhancement between NbSe2monolayers.

The interplay between charge transfer and electronic disorder in transition-metal dichalcogenide multilayers gives rise to superconductive coupling driven by proximity enhancement, tunneling and superconducting fluctuations, of a yet unwieldy variety. Artificial spacer layers introduced with atomic precision change the density of states by charge transfer. Here, we tune the superconductive coupling betweenNbSe2monolayers from proximity-enhanced to tunneling-dominated. We correlate normal and superconducting properties inSnSe1+δmNbSe21tailored multilayers with varying SnSe layer thickness (m=1-15). From high-field magnetotransport the critical fields yield Ginzburg-Landau coherence lengths with an increase of140%cross-plane (m=1-9), trending towards two-dimensional superconductivity form>9. We show cross-overs between three regimes: metallic with proximity-enhanced coupling (m=1-4), disordered-metallic with intermediate coupling (m=5-9) and insulating with Josephson tunneling (m>9). Our results demonstrate that stacking metal mono- and dichalcogenides allows to convert a metal/superconductor into an insulator/superconductor system, prospecting the control of two-dimensional superconductivity in embedded layers.

Suicide risk assessment: time to think again?

This paper considers recent research on suicide risk assessment to support calls for a 'rethink' of our assessment of the patients in our care, along with the adoption of a more collaborative approach to care planning with service users who remain at risk of self-harm and in need of a plan for their safety.

Admission patterns in a psychiatric intensive care unit in Ireland: a longitudinal follow-up.

OBJECTIVE: This study aims to describe the course of admission and clinical characteristics of admissions to a psychiatric intensive care unit (PICU) in the Phoenix Care Centre (PCC), Dublin, Ireland. METHODS: This retrospective chart study was conducted at the PCC, Dublin, Ireland. The cohort included all admission episodes (n = 91 complete data) over a three-year study period between January 2014 and January 2017. RESULTS: The mean age of admitted cases was 37.1 (s.d. = 11.3; range 18-63). The mean length of stay (LOS) was 59.3 days (s.d. = 61.0; median 39.5 days). All patients were admitted under Mental Health Act legislation. Antipsychotic polypharmacy was used in 61% (n = 55) of the admissions. A diagnosis of acute psychotic disorder (B = -1.027, p = 0.003, 95% CI: -1.691, -0.363) was associated with reduced LOS in PICU. CONCLUSION: Our study describes the cohort of patients admitted as being predominantly male, younger-aged, single, having a diagnosis of schizophrenia and being legally detained. The primary indication for referral is risk of assault, which highlights the need for the intensive and secure treatment model that a PICU can provide.

Charge transfer in (PbSe)1+δ (NbSe2)2 and (SnSe)1+δ (NbSe2)2 ferecrystals investigated by photoelectron spectroscopy.

Rotationally disordered, layered (PbSe)[Formula: see text](NbSe2)2 and (SnSe)[Formula: see text](NbSe2)2 ferecrystal heterostructures, consisting of stacked two-dimensional bilayers of either PbSe or SnSe alternating with two planes of NbSe2, were synthesized from modulated elemental reactants. The electronic structure of these ternary systems was investigated using x-ray photoelectron spectroscopy and compared to the binary bulk compounds PbSe, SnSe and NbSe2. The Pb and Sn core level spectra show a significant shift towards lower binding energies and the peak shape becomes asymmetric in the ferecrystals, while the electronic structure of the NbSe2 layers does not change compared to the bulk. This is interpreted in terms of an interlayer interaction in the form of a charge transfer of electrons from PbSe or SnSe into the NbSe2 layers, which is supported by valence band spectra and is consistent with prior results from transport measurements.

Superconducting ferecrystals: turbostratically disordered atomic-scale layered (PbSe)1.14(NbSe2)n thin films.

Hybrid electronic heterostructure films of semi- and superconducting layers possess very different properties from their bulk counterparts. Here, we demonstrate superconductivity in ferecrystals: turbostratically disordered atomic-scale layered structures of single-, bi- and trilayers of NbSe2 separated by PbSe layers. The turbostratic (orientation) disorder between individual layers does not destroy superconductivity. Our method of fabricating artificial sequences of atomic-scale 2D layers, structurally independent of their neighbours in the growth direction, opens up new possibilities of stacking arbitrary numbers of hybrid layers which are not available otherwise, because epitaxial strain is avoided. The observation of superconductivity and systematic Tc changes with nanostructure make this synthesis approach of particular interest for realizing hybrid systems in the search of 2D superconductivity and the design of novel electronic heterostructures.

Designed Synthesis of van der Waals Heterostructures: The Power of Kinetic Control.

Selecting specific 2D building blocks and specific layering sequences of van der Waals heterostructures should allow the formation of new materials with designed properties for specific applications. Unfortunately, the synthetic ability to prepare such structures at will, especially in a manner that can be manufactured, does not exist. Herein, we report the targeted synthesis of new metal-semiconductor heterostructures using the modulated elemental-reactant technique to nucleate specific 2D building blocks, control their thickness, and avoid epitaxial structures with long-range order. The building blocks, VSe2 and GeSe2 , have different crystal structures, which inhibits cation intermixing. The precise control of this approach enabled us to synthesize heterostructures containing GeSe2 monolayers alternating with VSe2 structural units with specific sequences. The transport properties systematically change with nanoarchitecture and a charge-density wave-like transition is observed.

The Influence of Interfaces on Properties of Thin-Film Inorganic Structural Isomers Containing SnSe-NbSe2 Subunits.

Inorganic isomers ([SnSe]1+δ)m(NbSe2)n([SnSe]1+δ)p(NbSe2)q([SnSe]1+δ)r(NbSe2)s where m, n, p, q, r, and s are integers and m + p + r = n + q + s = 4 were prepared using the modulated elemental reactant technique. This series of all six possible isomers provides an opportunity to study the influence of interface density on properties while maintaining the same unit cell size and composition. As expected, all six compounds were observed to have the same atomic compositions and an almost constant c-axis lattice parameter of ≈4.90(5) nm, with a slight trend in the c-axis lattice parameter correlated with the different number of interfaces in the isomers: two, four and six. The structures of the constituents in the ab-plane were independent of one another, confirming the nonepitaxial relationship between them. The temperature dependent electrical resistivities revealed metallic behavior for all the six compounds. Surprisingly, the electrical resistivity at room temperature decreases with increasing number of interfaces. Hall measurements suggest this results from changes in carrier concentration, which increases with increasing thickness of the thickest SnSe block in the isomer. Carrier mobility scales with the thickness of the thickest NbSe2 block due to increased interfacial scattering as the NbSe2 blocks become thinner. The observed behavior suggests that the two constituents serve different purposes with respect to electrical transport. SnSe acts as a charge donor and NbSe2 acts as the charge transport layer. This separation of function suggests that such heterostructures can be designed to optimize performance through choice of constituent, layer thickness, and layer sequence. A simplistic model, which predicts the properties of the complex isomers from a weighted sum of the properties of building blocks, was developed. A theoretical model is needed to predict the optimal compound for specific properties among the many potential compounds that can be prepared.

Charge transfer vs. dimensionality: what affects the transport properties of ferecrystals?

A series of ([SnSe]1+δ)m(NbSe2)2 compounds with two layers of NbSe2 separated by m bilayers of SnSe, where 1 ≤ m ≤ 20, were prepared from modulated precursors by systematically changing the number of SnSe layers in the repeating unit. A change in the c-lattice parameter of 0.579(3) nm per SnSe bilayer was observed. The thickness of the NbSe2 layer was determined to be 1.281(4) nm: twice the value of a single NbSe2 layer. HAADF-STEM images revealed the presence of extensive rotational disorder and the lack of any epitaxial relationship among the constituent layers. Two different coordination environments for the Nb in NbSe2 (trigonal prismatic and octahedral) were observed. The electrical resistivity increases and the carrier concentration decreases in the ([SnSe]1+δ)m(NbSe2)2 compounds with increasing number of SnSe bilayers. The temperature dependence of the resistivity suggests localization of carriers for higher m values. The decline in carrier concentration as a function of m implies the presence of charge transfer from SnSe to NbSe2. The transport properties of the ([SnSe]1+δ)m(NbSe2)2 compounds and the previously reported ([SnSe]1+δ)m(NbSe2)1 compounds both have unusually temperature independent resistivity compared to bulk NbSe2. Compounds with similar m/n ratios exhibit similar transport properties. Consequently, the dominant effect on the transport properties of ([SnSe]1+δ)m(NbSe2)2 is charge transfer, and there are only subtle differences between a monolayer and a bilayer of NbSe2.

Structure, stability, and properties of the intergrowth compounds ([SnSe]1+δ)m(NbSe2)n, where m = n = 1-20.

Intergrowth compounds of ([SnSe]1+δ)m(NbSe2)n, where 1 ≤ m = n ≤ 20, with the same atomic composition but different c-axis lattice parameters and number of interfaces per volume were synthesized using the modulated elemental reactant technique. A c-axis lattice parameter change of 1.217(6) nm as a function of one unit of m = n was observed. In-plane X-ray diffraction shows an increase in distortion of the rock salt layer as a function of m and a broadening of the NbSe2 reflections as n increases, indicating the presence of different coordination environments for Nb (trigonal prismatic and octahedral) and smaller crystallite size, which were confirmed via scanning transmission electron microscopy investigations. The electrical resistivities of all 12 compounds exhibit metallic temperature dependence and are similar in magnitude as would be expected for isocompositional compounds. Carrier concentration and mobility of the compounds vary within a narrow range of 2-6 × 10(21) cm(-3) and 2-6 cm(2) V(-1) s(-1), respectively. Even at a thickness of 12 nm for the SnSe and NbSe2 blocks, the properties of the intergrowth compounds cannot be explained as composite behavior, due to significant charge transfer between them. Upon being annealed at 500 °C, the higher order m = n compounds were found to convert to the thermodynamically stable phase, the (1,1) compound. This suggests that the capacitive energy of the interfaces stabilizes these intergrowth compounds.

Synthesis of inorganic structural isomers by diffusion-constrained self-assembly of designed precursors: a novel type of isomerism.

The structure of precursors is used to control the formation of six possible structural isomers that contain four structural units of PbSe and four structural units of NbSe2: [(PbSe)1.14]4[NbSe2]4, [(PbSe)1.14]3[NbSe2]3[(PbSe)1.14]1[NbSe2]1, [(PbSe)1.14]3[NbSe2]2[(PbSe)1.14]1[NbSe2]2, [(PbSe)1.14]2[NbSe2]3[(PbSe)1.14]2[NbSe2]1, [(PbSe)1.14]2[NbSe2]2[(PbSe)1.14]1[NbSe2]1[(PbSe)1.14]1[NbSe2]1, [(PbSe)1.14]2[NbSe2]1[(PbSe)1.14]1[NbSe2]2[(PbSe)1.14]1[NbSe2]1. The electrical properties of these compounds vary with the nanoarchitecture. For each pair of constituents, over 20,000 new compounds, each with a specific nanoarchitecture, are possible with the number of structural units equal to 10 or less. This provides opportunities to systematically correlate structure with properties and hence optimize performance.

Donor site morbidity post-conchal cartilage grafting.

Morbidity of the conchal cartilage donor site is evaluated in this article. Forty-two patients (from 1984-1994) with 44 donor sites were reviewed retrospectively. In 27 cases an anterior approach was used and in 17 cases a posterior approach was used. Four complications were observed: two cases of delayed healing in the post auricular approach, one case of flattening of the ear after an anterior approach, and one case with an anterior hypertrophic scar was seen. Only one case needed further surgical intervention. The anterior approach is technically easy, safe, and quick to perform but should be avoided in patients with a history or genetic predisposition to keloid or hypertrophic scars.

Aspergillus sinusitis in patients with AIDS: report of three cases and review.

Invasive aspergillosis is an uncommon but increasingly reported complication of AIDS. Sinusitis, usually bacterial in etiology, is frequently seen among human immunodeficiency virus (HIV)-infected patients. We discuss the cases of three patients with AIDS and invasive aspergillus sinusitis seen at our institutions and those of 15 patients who are described in the literature. Seven of the 18 had brain involvement, 3 had orbital involvement, and 7 had mastoid or other bony disease. Three had evidence of concomitant invasive pulmonary aspergillosis. Of 15 patients with evaluable histories, 11 had recognized risks for invasive aspergillosis; 6 had previous sinusitis, otitis, or polyposis; and 11 had prior conditions indicative of advanced HIV-related disease. Despite aggressive surgical intervention and systemic antifungal therapy, nearly all patients died as a result of aspergillosis.

Dermal and facial autografts in facial aesthetic surgery.

Results are presented of dermis grafts used in conjunction with surgery for aging changes in the face. During a two-year period grafts were used to correct crease lines in the glabella and nasolabial creases, as well as angles of the mouth and vermilion. Volume of the grafts was well maintained and very few complications occurred. This technique offers better long-term results than can be obtained by collagen or fat injections. The results and techniques are presented in detail.

Clinical use of Zyplast in correction of age- and disease-related contour deficiencies of the face.

The authors present their experience with the use of Zyplast (glutaraldehyde crosslinked collagen) for the treatment of skin creases in the aging face, lip augmentation, scars, and facial atrophy. One hundred female patients were studied over a nine-month period. The results were found to be superior in some aspects compared with Zyderm II collagen, but there is loss of correction after six months and repeated "top-up" injections are needed every four to six months to maintain a satisfactory cosmetic correction. Zyplast collagen has not reduced the number of patient visits nor the cost of treatment.

A simple technique for removing a silastic gel-filled breast implant through the axillary approach.

We present a simple, atraumatic technique for removing a breast implant through a small incision following transaxillary breast augmentation, using straight artery forceps with jaws covered with a length of soft rubber catheter. This provides a gentle but firm grasp on the silicone gel-filled prosthesis for easy removal, without rupture.

Energy cost of ambulation in healthy and disabled Filipino children.

The energy expenditures (Ee) for locomotion by nondisabled and disabled Filipino children aged 7 to 13 were determined and compared using indirect calorimetry. Forty-one controls (20 boys and 21 girls) ambulated at a comfortable pace; 16 children (eight boys and eight girls) with lower extremity poliomyelitis of varying severity ambulated by (1) wheelchair propulsion, (2) bilateral axillary crutches, (3) unilateral lower extremity ankle-foot orthoses or knee-ankle-foot orthoses, and (4) unassisted. Disabled children, regardless of their mode of ambulation, had to expend significantly more energy to ambulate than normal children (p less than 0.05). Wheelchair propulsion cost 16% more energy than the normal gait; crutch ambulation cost 41% more than the control. Children using unilateral braces sacrificed speed to attain near-normal Ee. When they ambulated without orthoses, their Ee increased by 109% over the control. In ascending order, the least energy was expanded by normal ambulation followed by disabled ambulation with unilateral brace, disabled propelling a wheelchair, disabled ambulation with bilateral axillary crutches, and disabled ambulation without brace. Efficiency of locomotion was reflected in the values obtained for Ee in terms of kcal x 10(-3)/kg/m, as demonstrated by the lower Ee but slower ambulation of children with braces, as compared to the nondisabled children.

Phalloplasty using the free radial forearm flap.

Our experience of phalloplasty using the radial forearm flap in five transsexual cases is reported. The results are disappointing due to the high incidence of complications. We had partial success in two cases, both complicated by a fistula, and complete failure in three cases due to vascular thrombosis.

A method of phalloplasty using the deep inferior epigastric flap.

Penile reconstruction remains a difficult surgical problem. To produce a phallus capable of erection and with a water-tight urethra to the tip has not been solved satisfactorily even by the introduction of free flap transfers. We present a method used in four cases, three transsexuals and one pseudohermaphrodite, in which a phallus was successfully constructed using the deep inferior epigastric flap.

Use of Orthoplast as nasal splint.

Nasal splintage is routinely employed in standard rhinoplasty. For 3 years one of the authors has used Orthoplast as an alternative to plaster of Paris, which has proved to have many advantages.